RNA-dependent chromatin localization of KDM4D lysine demethylase promotes H3K9me3 demethylation

The JmjC-containing lysine demethylase, KDM4D, demethylates di-and tri-methylation of histone H3 on lysine 9 (H3K9me3). How KDM4D is recruited to chromatin and recognizes its histone substrates remains unknown. Here, we show that KDM4D binds RNA independently of its demethylase activity. We mapped two non-canonical RNA binding domains: the first is within the N-terminal spanning amino acids 115 to 236, and the second is within the C-terminal spanning amino acids 348 to 523 of KDM4D. We also demonstrate that RNA interactions with KDM4D N-terminal region are critical for its association with chromatin and subsequently for demethylating H3K9me3 in cells. This study implicates, for the first time, RNA molecules in regulating the levels of H3K9 methylation by affecting KDM4D association with chromatin.     

Functional diversity of microboring Ostreobium algae isolated from corals

The filamentous chlorophyte Ostreobium sp. dominates shallow marine carbonate microboring communities, and is one of the major agents of reef bioerosion. While its large genetic diversity has emerged, its physiology remains little known, with unexplored relationship between genotypes and phenotypes (endolithic versus free-living growth forms). Here, we isolated nine strains affiliated to two lineages of Ostreobium (>8% sequence divergence of the plastid gene rbcL), one of which was assigned to the family Odoaceae, from the fast-growing coral host Pocillopora acuta Lamarck 1816. Free-living isolates maintained their bioerosive potential, colonizing pre-bleached coral carbonate skeletons. We compared phenotypes, highlighting shifts in pigment and fatty acid compositions, carbon to nitrogen ratios and stable isotope compositions (δ¹³C and δ¹⁵N). Our data show a pattern of higher chlorophyll b and lower arachidonic acid (20:4ω6) content in endolithic versus free-living Ostreobium. Photosynthetic carbon fixation and nitrate uptake, quantified via 8 h pulse-labeling with ¹³C-bicarbonate and ¹⁵N-nitrate, showed lower isotopic enrichment in endolithic compared to free-living filaments. Our results highlight the functional plasticity of Ostreobium phenotypes. The isotope tracer approach opens the way to further study the biogeochemical cycling and trophic ecology of these cryptic algae at coral holobiont and reef scales.     

Influence of habitat features and hunter behavior on white-tailed deer harvest

Sport hunting may help in controlling cervid populations over large areas. As with natural predators, several environmental factors can influence sport harvest. A better understanding of the environmental variables that limit the efficiency of sport hunting could provide guidelines for more efficient wildlife management using hunting. We studied white-tailed deer (Odocoileus virginianus) hunting on a high deer density island where hunting was the sole form of predation. Our objective was to study the behavior of sport hunters and determine the habitat characteristics (e.g., abundance of deer forage, visibility of the deer from the hunter's point of view, and accessibility of the territory to hunters) that are associated with a successful harvest. We collected movements and harvest site location data from 477 hunters equipped with handheld Global Positioning System (GPS) units. Harvest sites were visited and characterized, along with a paired random site, to determine the environmental conditions associated with a successful hunt. We also developed a model to predict the daily number of deer seen by hunters considering weather conditions, hunter characteristics (e.g., age, experience), and date of hunting. We used the mean number of deer seen per hunter per day as a relative index of local density in each hunted territory. At both the site and landscape scales, the combination of visibility and access had a positive effect on the distribution of harvested deer. Habitat types with less visual obstruction from vegetation enabled hunters to see more deer in a given day. At the site scale, harvested deer were located in areas with a lower density of access routes compared to areas where hunters travelled throughout the day. Using an innovative approach of studying hunter behavior with GPS technology, digital maps, and questionnaires, we highlighted the factors associated with hunter success. Our study suggests that habitat characteristics could be modified to increase harvest by improving accessibility and visibility near roads. Creating openings in mature and regenerating forest near access roads could make sport hunting a more efficient management tool, but the potential impact of increased forage availability in forest openings should not be overlooked. © 2012 The Wildlife Society.     

Detours by the blind mole-rat follow assessment of location and physical properties of underground obstacles

Orientation by an animal inhabiting an underground environment must be extremely efficient if it is to contend effectively with the high energetic costs of excavating soil for a tunnel system. We examined, in the field, the ability of a fossorial rodent, the blind mole-rat, Spalax ehrenbergi, to detour different types of obstacles blocking its tunnel and rejoin the disconnected tunnel section. To create obstacles, we dug ditches, which we either left open or filled with stone or wood. Most (77%) mole-rats reconnected the two parts of their tunnel and accurately returned to their orginal path by digging a parallel bypass tunnel around the obstacle at a distance of 10-20 cm from the open ditch boundaries or 3-8 cm from the filled ditch boundaries. When the ditch was placed asymmetrically across the tunnel, the mole-rats detoured around the shorter side. These findings demonstrate that mole-rats seem to be able to assess the nature of an obstacle ahead and their own distance from the obstacle boundaries, as well as the relative location of the far section of disconnected tunnel. We suggest that mole-rats mainly use reverberating self-produced seismic vibrations as a mechanism to determine the size, nature and location of the obstacle, as well as internal self-generated references to determine their location relative to the disconnected tunnel section. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.      

How emotion strengthens the recollective experience: a time-dependent hippocampal process

Emotion significantly strengthens the subjective recollective experience even when objective accuracy of the memory is not improved. Here, we examine if this modulation is related to the effect of emotion on hippocampal-dependent memory consolidation. Two critical predictions follow from this hypothesis. First, since consolidation is assumed to take time, the enhancement in the recollective experience for emotional compared to neutral memories should become more apparent following a delay. Second, if the emotion advantage is critically dependent on the hippocampus, then the effects should be reduced in amnesic patients with hippocampal damage. To test these predictions we examined the recollective experience for emotional and neutral photos at two retention intervals (Experiment 1), and in amnesics and controls (Experiment 2). Emotional memories were associated with an enhancement in the recollective experience that was greatest after a delay, whereas familiarity was not influenced by emotion. In amnesics with hippocampal damage the emotion effect on recollective experience was reduced. Surprisingly, however, these patients still showed a general memory advantage for emotional compared to neutral items, but this effect was manifest primarily as a facilitation of familiarity. The results support the consolidation hypothesis of recollective experience, but suggest that the effects of emotion on episodic memory are not exclusively hippocampally mediated. Rather, emotion may enhance recognition by facilitating familiarity when recollection is impaired due to hippocampal damage.