The role of glutamate signaling in incentive salience: second‐by‐second glutamate recordings in awake Sprague‐Dawley rats

The attribution of incentive salience to reward‐predictive stimuli has been shown to be associated with substance abuse‐like behavior such as increased drug taking. Evidence suggests that glutamate neurotransmission and sequential N‐methyl‐D‐aspartate (NMDA) activation are involved in the attribution of incentive salience. Here, we further explore the role of second‐by‐second glutamate neurotransmission in the attribution of incentive salience to reward‐predictive stimuli by measuring sign‐tracking behavior during a Pavlovian conditioned approach procedure using ceramic‐based microelectrode arrays configured for sensitive measures of extracellular glutamate in awake behaving Sprague‐Dawley rats. Specifically, we show that there is an increase in extracellular glutamate levels in the prelimbic cortex (PrL) and the nucleus accumbens core (NAcC) during sign‐tracking behavior to a food‐predictive conditioned stimulus (CS+) compared to the presentation of a non‐predictive conditioned stimulus (CS?). Furthermore, the results indicate greater increases in extracellular glutamate levels in the PrL compared to NAcC in response to the CS+, including differences in glutamate release and signal decay. Taken together, the present research suggests that there is differential glutamate signaling in the NAcC and PrL during sign‐tracking behavior to a food‐predictive CS+.

     

Estimation of hurdle clearance parameters using a monocular human motion tracking method

This paper presents a method of monocular human motion tracking for estimation of hurdle clearance kinematic parameters. The analysis involved 10 image sequences of five hurdlers at various training levels. Recording of the sequences was carried out under simulated starting conditions of a 110 m hurdle race. The parameters were estimated using the particle swarm optimization algorithm and they are based on analysis of the images recorded with a 100 Hz camera. The proposed method does not involve using any special clothes, markers, inertial sensors, etc. As the quality criteria, the mean absolute error and mean relative error were used. The level of computed errors justifies the use of this method to estimate hurdle clearance parameters.     

Varying foraging patterns in response to competition? A multicolony approach in a generalist seabird

Reducing resource competition is a crucial requirement for colonial seabirds to ensure adequate self‐ and chick‐provisioning during breeding season. Spatial segregation is a common avoidance strategy among and within species from neighboring breeding colonies. We determined whether the foraging behaviors of incubating lesser black‐backed gulls (Larus fuscus) differed between six colonies varying in size and distance to mainland, and whether any differences could be related to the foraging habitats visited. Seventy‐nine incubating individuals from six study colonies along the German North Sea coast were equipped with GPS data loggers in multiple years. Dietary information was gained by sampling food pellets, and blood samples were taken for stable isotope analyses. Foraging patterns clearly differed among and within colonies. Foraging range increased with increasing colony size and decreased with increasing colony distance from the mainland, although the latter might be due to the inclusion of the only offshore colony. Gulls from larger colonies with consequently greater density‐dependent competition were more likely to forage at land instead of at sea. The diets of the gulls from the colonies furthest from each other differed, while the diets from the other colonies overlapped with each other. The spatial segregation and dietary similarities suggest that lesser black‐backed gulls foraged at different sites and utilized two main habitat types, although these were similar across foraging areas for all colonies except the single offshore island. The avoidance of intraspecific competition results in colony‐specific foraging patterns, potentially causing more intensive utilization of terrestrial foraging sites, which may offer more predictable and easily available foraging compared with the marine environment.     

GPS tracking data of Lesser Black-backed Gulls and Herring Gulls breeding at the southern North Sea coast

In this data paper, Bird tracking - GPS tracking of Lesser Black-backed Gulls and Herring Gulls breeding at the southern North Sea coast is described, a species occurrence dataset published by the Research Institute for Nature and Forest (INBO). The dataset (version 5.5) contains close to 2.5 million occurrences, recorded by 101 GPS trackers mounted on 75 Lesser Black-backed Gulls and 26 Herring Gulls breeding at the Belgian and Dutch coast. The trackers were developed by the University of Amsterdam Bird Tracking System (UvA-BiTS, http://www.uva-bits.nl). These automatically record and transmit bird movements, which allows us and others to study their habitat use and migration behaviour in great detail. Our bird tracking network is operational since 2013. It is funded for LifeWatch by the Hercules Foundation and maintained in collaboration with UvA-BiTS and the Flanders Marine Institute (VLIZ). The recorded data are periodically released in bulk as open data (http://dataset.inbo.be/bird-tracking-gull-occurrences), and are also accessible through CartoDB and the Global Biodiversity Information Facility (GBIF).     

Autumn migration of Montagu’s harriers Circus pygargus tracked by satellite telemetry

Although there is a general understanding of Montagu’s harriers migration routes and wintering areas, detailed information on the species’ migration is still lacking. However, improvements in satellite tracking technology in recent years, have enabled the study of medium-sized species by means of satellite telemetry. In 2006, ten adult Montagu’s harriers were fitted with satellite transmitters in northeastern Spain and tracked during their autumn migration to their wintering grounds in sub-Saharan Africa. The migration took between 10 and 30 days, and the end point was determined using breakpoint regressions. Whereas some birds had stopovers of more than a week, others stayed at the same site for only 1 or 2 days at the most. The tagged birds ultimately established at wintering grounds located along the border of Mauritania with Mali and Senegal, a distance of nearly 3000 km from the breeding sites. These sites are situated within a small range of latitudes (14° and 17°N), although distributed over a wider range of longitudes (−15°E and −4°E), with some birds occupying sites more than 1000 km apart. The distance covered in 1 day during the migration ranged between 93 and 219 km, with peaks of traveling speed of up to 65 km/h. Harriers were recorded traveling only during daytime, covering the longest distances in the late afternoon, suggesting that they are daytime migrants. Most of the distance was covered between 1500 and 2000 hours, and no traveling was recorded between 2000 and 0500 hours. During migration, harriers flew close to the ground (40–100 m on average). Improved knowledge of the harriers’ exact wintering sites may provide insights on the problems Montagu’s harriers face during the winter, highlighting the need to take into account what happens in both the breeding and wintering grounds to implement successful conservation measures.     

Further work on the cryopreservation of articular cartilage with particular reference to the liquidus tracking (LT) method

The cryopreservation of articular cartilage with survival of living cells has been a difficult problem. We have provided evidence that this is due to the formation of ice crystals in the chondrons. We have developed a method in which the concentration of the cryoprotectant dimethyl sulphoxide (Me(2)SO) is increased progressively, in steps, as cooling proceeds so that ice is never allowed to form, but the very high concentrations of Me(2)SO required at low temperatures are reached only at those low temperatures. In this paper, we describe some new experiments with discs of ovine articular cartilage similar to those used in our previous studies and we show that continuous stirring throughout the process resulted in a significant increase in the rate of (35)S sulphate incorporation into glycosoaminoglycans (GAGs), now reaching 87% of the corresponding fresh control values. We confirmed that the method is also effective for human knee joint cartilage, which gave 70% of fresh control ability to synthesise GAGs; continuous stirring was also used in this experiment. We then extended the method to ovine knee joint osteochondral dowels and showed that, again with continuous stirring, the method produced tissue concentrations of Me(2)SO that were sufficient to prevent freezing in dowels too, and to permit cell function at 60% of control. The most important mechanical property (instantaneous compressive modulus) was unaffected by the process. Finally, we experimented with some technical variations to facilitate clinical use-a more rapid process for warming and removal of Me(2)SO was developed and a method of short-term storage before or after cryopreservation was developed. Finally, pilot experiments were carried out to provide proof of principle for a closed, continuous flow method in which both temperature and Me(2)SO concentration were computer-controlled.     

Evidence of olfactory antagonistic imposition as a facilitator of evolutionary shifts in pheromone blend usage in Ostrinia spp. (Lepidoptera: Crambidae)

Olfactory receptor neuron (ORN) response was measured to assess why some males ("rare males") of the Asian corn borer (ACB), Ostrinia furnacalis, have a broad behavioral response to fly upwind to both the ACB and the European corn borer (ECB), Ostrinia nubilalis, pheromone blends. We performed single-sensillum electrophysiological recordings on ACB males that had been behaviorally assessed for upwind flight response to the ACB blend [60:40 (Z)-12-tetradecenyl acetate (Z12-14:OAc) to (E)-12-tetradecenyl acetate (E12-14:OAc)], as well as to ECB (Z-strain) and ECB (E-strain) blends [3:97 and 99:1 (Z)-11-tetradecenyl acetate (Z11-14:OAc) to (E)-11-tetradecenyl acetate (E11-14:OAc)]. Sensilla from all types of males had large- and small-spike-sized ORNs responding strongly to Z12- or E12-14:OAc, but weakly to Z11- and E11-14:OAc. In the majority of males ("normal males") that flew upwind only to the ACB blend, Z11-14:OAc elicited responses in an intermediate spike-sized ORN associated with behavioral antagonism that is mainly tuned to (Z)-9-tetradecenyl acetate (Z9-14:OAc). In the rare-type ACB males that flew to both the ACB and ECB pheromone blends, Z11-14:OAc did not stimulate this ORN. Increased responsiveness to ancestral pheromone components by ORNs associated with behavioral antagonism could be instrumental in reproductive character displacement, or in reinforcement and reproductive isolation during speciation by helping to increase assortative mating between males and females in derived populations that use novel sex pheromone blends.     

Altered olfactory receptor neuron responsiveness in rare Ostrinia nubilalis males attracted to the O. furnacalis pheromone blend

Three percent of E-strain Ostrinia nubilalis males fly upwind in response to the Ostrinia furnacalis pheromone blend [a 40:60 ratio of (E)-12-tetradecenyl acetate to (Z)-12-tetradecenyl acetate (E12-14:OAc to Z12-14:OAc)], in addition to their own pheromone blend [a 99:1 ratio of (E)-11-tetradecenyl acetate to (Z)-11-tetradecenyl acetate) (E11-14:OAc to Z11-14:OAc)]. We assessed the olfactory receptor neuron (ORN) responses of these behaviorally "rare" males versus those of normal males. For the three ORNs housed within each sensillum, we tested responsiveness to Z12-14:OAc, E12-14:OAc, Z11-14:OAc, E11-14:OAc, and the behavioral antagonist (Z)-9-tetradecenyl acetate (Z9-14:OAc). Z11-14:OAc, E11-14:OAc, and Z9-14:OAc stimulated ORNs exhibiting distinct small, large, and medium spike sizes, respectively. For rare and normal males, both Z12-14:OAc and E12-14:OAc usually elicited responses from the largest-spiking ORN. In many ORNs of normal males, Z12-14:OAc or E12-14:OAc stimulated the smaller-spiking ORN that is responsive to Z11-14:OAc. In rare males, detectable ORN responses from the smaller-spiking ORN in response to Z12- and E12-14:OAc were virtually non-existent. These differences in ORN tuning in rare males will tend to create an ORN firing ratio between the large- and small-spiking ORNs in response to the O. furnacalis blend that is similar to that elicited by the O. nubilalis blend.     

The transport of alpha(1A)-adrenergic receptor with 33-nm step size in live cells

We used the technique of single particle tracking (SPT) with high tempo-spatial resolution to efficiently explore the route and mechanism for the transport of alpha(1A)-adrenergic receptor (alpha(1A)-AR) in real time in living cells. We found that the initial transport of alpha(1A)-AR in cells depended on actin filaments with the velocity of 0.2 microm/s and exhibited discrete 33-nm steps. It was noted that the step size, the rate constant, and the velocities were in accordance with the character of single myosin in vitro, implying that while transporting each endosome myosins did not work in the "tug-of-war" mode and that they did not adopt the strategy to boost up transporting speed by working coordinately. These results provided insight into the mechanism of GPCR transport in vivo.     

Sensitive detection of GFP utilizing tyramide signal amplification to overcome gene silencing

The green fluorescent protein (GFP) is among the most commonly used expression markers in biology. GFP-tagged cells have played a particularly important role in studies of cell lineage. Sensitive detection of GFP is crucially important for such studies to be successful, and problems with detection may account for discrepancies in the literature regarding the possible fate choices of stem cells. Here we describe a very sensitive technique for visualization of GFP. Using it we can detect about 90% of cells of donor origin while we could only see about 50% of these cells when we employ the methods that are in general use in other laboratories. In addition, we provide evidence that some cells permanently silence GFP expression. In the case of the progeny of bone marrow stem cells, it appears that the more distantly related they are to their precursors, the more likely it is that they will turn off the lineage marker.