School density affects the strength of collective avoidance responses in wild-caught Atlantic herring Clupea harengus: a simulated predator encounter experiment

An experimental study in a semi-controlled environment was conducted to examine whether school density in wild-caught Atlantic herring Clupea harengus affects the strength of their collective escape behaviours. Using acoustics, the anti-predator diving responses of C. harengus in two schools that differed in density were quantified by exposing them to a simulated threat. Due to logistical restrictions, the first fish was tested in a low-density school condition (four trials; packing density = 1.5 fish m(-3); c. 6000 fish) followed by fish in a high-density school condition (five trials; packing density = 16 fish m(-3); c. 60 000 fish). The C. harengus in a high-density school exhibited stronger collective diving avoidance responses to the simulated predators than fish in the lower-density school. The findings suggest that the density (and thus the internal organization) of a fish school affects the strength of collective anti-predatory responses, and the extent to which information about predation risk is transferred through the C. harengus school. Therefore, the results challenge the common notion that information transfer within animal groups may not depend on group size and density.

Some Possible Cases of Escape Mimicry in Neotropical Butterflies

The possibility that escape or evasive mimicry evolved in butterflies and other prey insects in a similar fashion to classical Batesian and Müllerian mimicry has long been advanced in the literature. However, there is a general disagreement among lepidopterists and evolutionary biologists on whether or not escape mimicry exists, as well as in which mimicry rings this form of mimicry has evolved. Here, we review some purported cases of escape mimicry in Neotropical butterflies and suggest new mimicry rings involving several species of Archaeoprepona, Prepona, and Doxocopa (the "bright blue bands" ring) and species of Colobura and Hypna (the "creamy bands" ring) where the palatability of butterflies, their ability to escape predator attacks, geographic distribution, relative abundance, and co-occurrence in the same habitats strongly suggest that escape mimicry is involved. In addition, we also indicate other butterfly taxa whose similarities of coloration patterns could be due to escape mimicry and would constitute important case studies for future investigation.

Characterization of sleep in Aplysia californica

STUDY OBJECTIVE

To characterize sleep in the marine mollusk, Aplysia californica.

DESIGN

Animal behavior and activity were assessed using video recordings to measure activity, resting posture, resting place preference, and behavior after rest deprivation. Latencies for behavioral responses were measured for appetitive and aversive stimuli for animals in the wake and rest states.

SETTING

Circadian research laboratory for Aplysia.

PATIENTS OR PARTICIPANTS

A. californica from the Pacific Ocean.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Aplysia rest almost exclusively during the night in a semi-contracted body position with preferential resting locations in the upper corners of their tank. Resting animals demonstrate longer latencies in head orientation and biting in response to a seaweed stimulus and less frequent escape response steps following an aversive salt stimulus applied to the tail compared to awake animals at the same time point. Aplysia exhibit rebound rest the day following rest deprivation during the night, but not after similar handling stimulation during the day.

CONCLUSIONS

Resting behavior in Aplysia fulfills all invertebrate characteristics of sleep including: (1) a specific sleep body posture, (2) preferred resting location, (3) reversible behavioral quiescence, (4) elevated arousal thresholds for sensory stimuli during sleep, and (5) compensatory sleep rebound after sleep deprivation.

Examining the operant function of challenging behavior in young males with fragile X syndrome: a summary of 12 cases

This study used experimental functional analyses to examine the operant function of challenging behaviors exhibited by 12 males (ages 27-51 months) with fragile X syndrome (FXS). Eight children met criteria for negatively reinforced challenging behavior in the form of escape from demands and/or escape from social interactions. Nine children met criteria for positively reinforced challenging behavior in the form of obtaining access to highly preferred items. Attention was identified as a maintaining consequence for three children. The functional analysis was inconclusive for one child. Results suggest that, for young males with FXS, challenging behaviors may more likely be tangibly and escape maintained than attention maintained. Our findings affirm past research suggesting a unique behavioral phenotype for this population.

Neural responses from the wind-sensitive interneuron population in four cockroach species

The wind-sensitive insect cercal sensory system is involved in important behaviors including predator detection and initiating terrestrial escape responses as well as flight maintenance. However, not all insects possessing a cercal system exhibit these behaviors. In cockroaches, wind evokes strong terrestrial escape responses in Periplaneta americana and Blattella germanica, but only weak escape responses in Blaberus craniifer and no escape responses in Gromphadorhina portentosa. Both P. americana and B. craniifer possesses pink flight muscles correlated with flight ability while B. germanica possesses white flight muscles that cannot support flight and G. portentosa lacks wings. These different behavioral combinations could correlate with differences in sensory processing of wind information by the cercal system. In this study, we focused on the wind-sensitive interneurons (WSIs) since they provide input to the premotor/motor neurons that influence terrestrial escape and flight behavior. Using extracellular recordings, we characterized the responses from the WSI population by generating stimulus-response (S-R) curves and examining spike firing rates. Using cluster analysis, we also examined the activity of individual units (four per species, though not necessarily homologous) comprising the population response in each species. Our main results were: (1) all four species possessed ascending WSIs in the abdominal connectives; (2) wind elicited the weakest WSI responses (lowest spike counts and spike rates) in G. portentosa; (3) wind elicited WSI responses in B. craniifer that were greater than P. americana or B. germanica; (4) the activity of four individual units comprising the WSI population response in each species was similar across species.

Predation of Anastrepha ludens (Diptera: Tephritidae) by Norops serranoi (Reptilia: Polychrotidae): functional response and evasion ability

The Mexican fruit fly, Anastrepha ludens (Loew), is one of the 10 worldwide more important fruit crop pests. Orchards of southeastern Chiapas also shelter the tree-dwelling lizard Norops serranoi (Köhler), which likely prey upon these flies. In standard laboratory conditions, we determined the functional response of four male and four female lizards on mass-reared fruit flies. We used a general logistic analysis of proportion of killed prey versus available prey to determine the shape of the functional response. Male lizards showed a type II functional response, while females showed a type III functional response. For the highest fruit fly densities, female lizards caught significantly more fruit flies than males did. The predator evasion ability and the survival of mass-reared and wild fruit flies were compared. Wild fruit flies evaded more male lizard attacks than mass-reared flies. However, when female lizards attacked, there was no significant difference between strains. Fruit flies survival was higher with male than with female lizards, but it did not depend on fruit fly strains. This is the first report of a vertebrate preying on the Mexican fruit fly, demonstrating that female lizards impose a higher predation pressure and are more efficient at capturing wild fruit flies than males. We discuss the implications of our results on mass-rearing and quality control of sterile flies.

Spectrum-specific UV egg damage and dispersal responses in the phytoseiid predatory mite Neoseiulus californicus (Acari: Phytoseiidae)

Solar ultraviolet-B (UVB) radiation is deleterious to plant-dwelling mites. Neoseiulus californicus (McGregor) is a predominant predator of agriculturally important pest species of spider mite. However, phytoseiid mites are more vulnerable to UVB radiation than spider mites. Thus, the UVB radiation may influence decision making in foraging phytoseiid mites whether disperse or not. We tested the difference in impact and behavioral response among wavelengths of monochromatic UV radiation using a spectroscopic light source in N. californicus in the laboratory. We also examined whether the behavioral responses of N. californicus females to UV radiation varied based on the presence of prey (Tetranychus urticae Koch) eggs and residues (webs and excreta of T. urticae: foraging cue). The impact of UV radiation on the N. californicus egg hatchability varied drastically between wavelengths of ≤300 nm (0%) and ≥310 nm (100%). The N. californicus females escaped from UV radiation more quickly when they were irradiated with UV at shorter wavelength. Presence of T. urticae eggs had no effects arresting the escape of phytoseiid mites. In contrast, prey residues (including eggs) markedly detained N. californicus females from escaping under UV irradiation at ≥310 nm. However, N. californicus females quickly escaped when irradiated with UV at harmful 300 nm wavelength, regardless of prey cues. This indicates that the eyeless phytoseiid mite is capable of perceiving UV radiation, and whether escape or not is determined on the basis of harmful/harmless UV wavelength and presence/absence of foraging cues.

Effects of covering behavior and exposure to a predatory crab Charybdis japonica on survival and HSP70 expression of juvenile sea urchins Strongylocentrotus intermedius

Predation is a complex process among predator, prey and environment. Juvenile sea urchins are more susceptible to predators than adults, which affects community structure. Behavior is involved in anti-predator responses by changes in the expression of anti-predator responsive genes. Here, we investigated the effects of exposure to a predatory crab Charybdis japonica and covering behavior on survival and HSP70 expression of juvenile sea urchins Strongylocentrotus intermedius. C. japonica consumed large numbers of juvenile S. intermedius in 12 hours with a mortality of 34.17±11.43%. Covering behavior did not significantly reduce predation. Exposure to C. japonica did not significantly upregulate HSP70 expression of juvenile S. intermedius in 12 hours. Covering behavior showed no significant regulative effect on the gene expression of HSP70 of juvenile S. intermedius exposed to C. japonica for 12 hours. The results indicate that the anti-predator function of covering behavior is limited and that HSP70 expression does not appear to play an important role in the anti-predator process of S. intermedius.

Nociceptive sensitization reduces predation risk

Sublethal injury triggers long-lasting sensitization of defensive responses in most species examined, suggesting the involvement of powerful evolutionary selection pressures [1]. In humans, this persistent nociceptive sensitization is often accompanied by heightened sensations of pain and anxiety [2]. While experimental [3] and clinical [4] evidence support the adaptive value of immediate nociception during injury, no direct evidence exists for adaptive benefits of long-lasting sensitization after injury. Recently, we showed that minor injury produces long-term sensitization of behavioral and neuronal responses in squid, Doryteuthis pealei [5, 6]. Here we tested the adaptive value of this sensitization during encounters between squid and a natural fish predator. Locomotion and other spontaneous behaviors of squid that received distal injury to a single arm (with or without transient anesthesia) showed no measurable impairment 6 hr after the injury. However, black sea bass given access to freely swimming squid oriented toward and pursued injured squid at greater distances than uninjured squid, regardless of previous anesthetic treatment. Once targeted, injured squid began defensive behavioral sequences [7, 8] earlier than uninjured squid. This effect was blocked by brief anesthetic treatment that prevented development of nociceptive sensitization [6, 9]. Importantly, the early anesthetic treatment also reduced the subsequent escape and survival of injured, but not uninjured, squid. Thus, while minor injury increases the risk of predatory attack, it also triggers a sensitized state that promotes enhanced responsiveness to threats, increasing the survival (Darwinian fitness) of injured animals during subsequent predatory encounters.

Optical stimulation of zebrafish hair cells expressing channelrhodopsin-2

Vertebrate hair cells are responsible for the high fidelity encoding of mechanical stimuli into trains of action potentials (spikes) in afferent neurons. Here, we generated a transgenic zebrafish line expressing Channelrhodopsin-2 (ChR2) under the control of the hair-cell specific myo6b promoter, in order to examine the role of the mechanoelectrical transduction (MET) channel in sensory encoding in afferent neurons. We performed in vivo recordings from afferent neurons of the zebrafish lateral line while activating hair cells with either mechanical stimuli from a waterjet or optical stimuli from flashes of ∼470-nm light. Comparison of the patterns of encoded spikes during 100-ms stimuli revealed no difference in mean first spike latency between the two modes of activation. However, there was a significant increase in the variability of first spike latency during optical stimulation as well as an increase in the mean number of spikes per stimulus. Next, we compared encoding of spikes during hair-cell stimulation at 10, 20, and 40-Hz. Consistent with the increased variability of first spike latency, we saw a significant decrease in the vector strength of phase-locked spiking during optical stimulation. These in vivo results support a physiological role for the MET channel in the high fidelity of first spike latency seen during encoding of mechanical sensory stimuli. Finally, we examined whether remote activation of hair cells via ChR2 activation was sufficient to elicit escape responses in free-swimming larvae. In transgenic larvae, 100-ms flashes of ∼470-nm light resulted in escape responses that occurred concomitantly with field recordings indicating Mauthner cell activity. Altogether, the myo6b:ChR2 transgenic line provides a platform to investigate hair-cell function and sensory encoding, hair-cell sensory input to the Mauthner cell, and the ability to remotely evoke behavior in free-swimming zebrafish.

The behavioural response of adult Petromyzon marinus to damage-released alarm and predator cues

Using semi-natural enclosures, this study investigated (1) whether adult sea lamprey Petromyzon marinus show avoidance of damage-released conspecific cues, damage-released heterospecific cues and predator cues and (2) whether this is a general response to injured heterospecific fishes or a specific response to injured P. marinus. Ten replicate groups of 10 adult P. marinus, separated by sex, were exposed to one of the following nine stimuli: deionized water (control), extracts prepared from adult P. marinus, decayed adult P. marinus (conspecific stimuli), sympatric white sucker Catostomus commersonii, Amazon sailfin catfish Pterygoplichthys pardalis (heterospecific stimuli), 2-phenylethylamine (PEA HCl) solution, northern water snake Nerodia sipedon washing, human saliva (predator cues) and an adult P. marinus extract and human saliva combination (a damage-released conspecific cue and a predator cue). Adult P. marinus showed a significant avoidance response to the adult P. marinus extract as well as to C. commersonii, human saliva, PEA and the adult P. marinus extract and human saliva combination. For mobile P. marinus, the N. sipedon washing induced behaviour consistent with predator inspection. Exposure to the P. pardalis extract did not induce a significant avoidance response during the stimulus release period. Mobile adult female P. marinus showed a stronger avoidance behaviour than mobile adult male P. marinus in response to the adult P. marinus extract and the adult P. marinus extract and human saliva combination. The findings support the continued investigation of natural damage-released alarm cue and predator-based repellents for the behavioural manipulation of P. marinus populations in the Laurentian Great Lakes.

Way-finding during a fire emergency: an experimental study in a virtual environment

The way-finding behaviour and response during a fire emergency in a virtual environment (VE) was experimentally investigated. Forty participants, divided into two groups, were required to find the emergency exit as soon as possible in a virtual hotel building because of a fire escape demand under condition 1 (VE without virtual fire, control group) and condition 2 (VE with virtual fire, treatment group). Compared to the control group, the treatment group induced significantly higher skin conductivity and heart rate, experienced more stress, took longer time to notice the evacuation signs, had quicker visual search and had a longer escape time to find the exit. These results indicated that the treatment condition induced higher physiological and psychological stress, and had influenced the escape behaviour compared to the control group. In practice, fire evacuation education and fire evacuation system design should consider the response characteristics in a fire emergency.

Seasonal colour and antipredator behaviour in Etheostoma (Percidae)

This study examined how colour varies across season and sex in the fantail darter Etheostoma flabellare and the banded darter Etheostoma zonale. Etheostoma flabellare has male-only parental care and exhibited slight sexual dimorphism in overall colour, with no discernible effect of season on colour; whereas E. zonale does not have parental care and exhibited substantial sexual dimorphism in colour, but only in the breeding season. Additionally, antipredator behaviour of E. zonale was compared between males that were fully coloured during the breeding season and males that were partially coloured at that time, but the effects of colour and season were not consistent across males.

Social support in pigs with different coping styles

The presence of a conspecific during a stressful situation, i.e. social support, can considerably lower the stress response of an individual compared to experiencing the stressful situation alone. Pigs also benefit from social support, but it is not known whether the extent to which they benefit is dependent on their personality or coping style. In this study, therefore, the effect of social support on behavioral and physiological (i.e. salivary cortisol, heart rate and the heart rate variability parameters standard deviation (SDNN) and root mean square of successive differences (RMSSD)) stress responses was studied in pigs with different coping styles. Based on the backtest, piglets were classified as high-resisting (HR) or low-resisting (LR). At 11weeks of age, 12 gilts of each coping style were subjected to a 15min restraint test in a weighing cage without a pen mate present (i.e. no support treatment) and 12 other gilts of each coping style were subjected to this test with a pen mate, a boar with the same coping style, present (i.e. support treatment). With the pen mate present, LR gilts showed less standing alert behavior and they had their ears back less often than without the pen mate present. On the other hand, HR gilts seemed to spend less time on escaping the cage and more HR gilts seemed to urinate in the situation when the pen mate was present than without the pen mate present, but this was not significant. Independently of the test situation, HR gilts grunted more than LR gilts and they were more likely to urinate than LR gilts. Salivary cortisol concentrations were not affected by treatment or coping style, but were increased at 30min after the start of the test after which concentrations decreased again to starting levels. The heart rate and heart rate variability parameters RMSSD and RMSSD/SDNN ratio were not affected by treatment or coping style, but the SDNN was lower in the LR pigs during the first and last 5min of the test when a pen mate was present than without the pen mate present. In addition, heart rate and heart rate variability were increased during the test compared to before and after the test. No differences in behavior and salivary cortisol concentrations were found between the HR and LR accompanying boars. Although effects of social support were not found on all variables measured, the results do indicate that pigs may benefit from social support during a stressful situation and that pigs with a low-resisting coping style will likely benefit more than pigs with a high-resisting coping style.

Responses to conflict, family loss and flight: posttraumatic stress disorder among unaccompanied refugee minors from Africa

OBJECTIVE

To investigate African unaccompanied refugee minors (URMs) living in Austria for posttraumatic stress disorder (PTSD) prevalence and related symptoms, comorbidity, demographics and coping strategies.

METHOD

"UCLA PTSD Index and inventories" and "Scales for Children Afflicted by War and Persecution (SCWP)" were used to assess 41 African URMs.

RESULTS

The study revealed lower PTSD rates than measured among URMs in previous studies. Girls were more likely to develop PTSD. PTSD was significantly correlated with single war-related traumatic events. The depression score for the sample was above the clinical cut-off value.

CONCLUSIONS

Trauma-specific psychopathology was less severe than reported in other studies. These findings could be explained by concepts of resilience. Other implications, such as response bias, are discussed.

Effects of vehicle speed on flight initiation by Turkey vultures: implications for bird-vehicle collisions

The avoidance of motorized vehicles is a common challenge for birds in the modern world. Birds appear to rely on antipredator behaviors to avoid vehicles, but modern vehicles (automobiles and aircraft) are faster than natural predators. Thus, birds may be relatively ill-equipped, in terms of sensory capabilities and behaviors, to avoid vehicles. We examined the idea that birds may be unable to accurately assess particularly high speeds of approaching vehicles, which could contribute to miscalculations in avoidance behaviors and ultimately cause collisions. We baited turkey vultures (Cathartes aura) to roads with animal carcasses and measured flight initiation distance and effective time-to-collision in response to a truck driving directly towards vultures from a starting distance of 1.13 km and at one of three speeds: 30, 60, or 90 kph (no vultures were struck). Flight initiation distance of vultures increased by a factor of 1.85 as speed increased from 30 to 90 kph. However, for 90-kph approaches there was no clear trend in flight initiation distance across replicates: birds appeared equally likely to initiate escape behavior at 40 m as at 220 m. Time-to-collision decreased by a factor of 0.62 with approach speeds from 30 to 90 kph. Also, at 90 kph, four vehicle approaches (17%) resulted in near collisions with vultures (time-to-collision ≤1.7 s), compared to none during 60 kph approaches and one during 30 kph approaches (4%). Our findings suggest that antipredator behaviors in turkey vultures, particularly stimulus processing and response, might not be well tuned to vehicles approaching at speeds ≥90 kph. The possible inability of turkey vultures to react appropriately to high-speed vehicles could be common among birds, and might represent an important determinant of bird-vehicle collisions.

Evidence for the Deflective Function of Eyespots in Wild Junonia evarete Cramer (Lepidoptera, Nymphalidae)

Junonia evarete Cramer is a fast-flying butterfly that perches on the ground with wings opened exhibiting four eyespots close to wing borders. These eyespots presumably function either to intimidate predators, like insectivorous birds, or to deflect bird attacks to less vital parts of the body. We assessed the form, frequency, and location of beak marks on the wings of wild butterflies in central Brazil during two not consecutive years. We found that almost 50% of males and 80% of females bore signals of predator attacks (wing tears), most of them consisting of partially or totally V-shaped forms apparently produced by birds. Males were significantly less attacked and showed a lower proportion of attacks on eyespots than females, suggesting they are better to escape bird attacks. In contrast, females were heavily attacked on eyespots. Eyespot tears in females were higher (and significant different) than expected by chance, indicating that birds do attempt to reach the eyespots when striking on these butterflies. Other comparisons involving the proportion of tears directed or not directed to eyespots in males and females are presented and discussed.

Hemodynamic and neuropathological analysis in rats with aluminum trichloride-induced Alzheimer's disease

BACKGROUND AND AIMS

Hemodynamic normality is crucial to maintaining the integrity of cerebral vessels and, therefore, preserving the cognitive functions of Alzheimer's disease patients. This study investigates the implications of the hemodynamic changes and the neuropathological diversifications of AlCl3-induced AD.

METHODS

The experimental animals were 8- to 12-wk-old male Wistar rats. The rats were randomly divided into 2 groups: a control group and a (+)control group. Food intake, water intake, and weight changes were recorded daily for 22 wk. Synchronously, the regional cerebral blood flow (rCBF) of the rats with AlCl3-induced AD were measured using magnetic resonance imaging (MRI). The hemorheological parameters were analyzed using a computerized auto-rotational rheometer. The brain tissue of the subjects was analyzed using immunohistological chemical (IHC) staining to determine the beta-amyloid (Aβ) levels.

RESULTS

The results of hemodynamic analysis revealed that the whole blood viscosity (WBV), fibrinogen, plasma viscosity and RBC aggregation index (RAI) in (+)control were significantly higher than that of control group, while erythrocyte electrophoresis (EI) of whole blood in (+)control were significantly lower than that of control group. The results of acetylcholinesterase-RBC (AChE-RBC)in the (+)control group was significantly higher than that of the control group. The results also show that the reduction of rCBF in rats with AlCl3-induced AD was approximately 50% to 60% that of normal rats. IHC stain results show that significantly more Aβ plaques accumulated in the hippocampus and cortex of the (+)control than in the control group.

CONCLUSION

The results accentuate the importance of hemorheology and reinforce the specific association between hemodynamic and neuropathological changes in rats with AlCl3-induced AD. Hemorheological parameters, such as WBV and fibrinogen, and AChE-RBC were ultimately proven to be useful biomarkers of the severity and progression of AD patients. In addition, the parameters can be substituted for invasive inspection in therapeutic intervention.

Serotonin transporter genotype (5-HTTLPR) and electrocortical responses indicating the sensitivity to negative emotional cues

Growing literature indicates that emotional reactivity and regulation are strongly linked to genetic modulation of serotonergic neurotransmission. However, until now, most studies have focused on the relationship between genotypic markers, in particular the serotonin transporter-linked polymorphic region (5-HTTLPR), and neural structures using MRI. The current study aimed to bridge the gap between the relevant MRI literature on the effects of the 5-HTTLPR genotype and the research tradition focusing on transient lateralized changes of electrocortical activity in the prefrontal cortex using electroencephalography (EEG). Lateral shifts of EEG alpha asymmetry in response to an aversive film consisting of scenes of real injury and death were assessed in healthy participants (n = 165). To evaluate the specificity of the 5-HTTLPR effect, participants were also tested for the COMT Val158Met polymorphism which is linked to dopamine inactivation. While viewing the film, individuals homozygous for the 5-HTTLPR short allele displayed a clear lateral shift of dorsolateral frontal activity to the right, which was virtually absent in participants carrying the long allele. The heightened electrocortical response to the aversive stimulation and its direction indicates a greater propensity of s/s homozygotes to experience withdrawal oriented affect in response to negative emotion cues in the environment. Moreover, together with previous research the findings support the notion of a link between the serotonergic system and self-regulation related to avoidance motivation, and a link between the dopaminergic system and self-regulation related to approach motivation.

Monitoring escape and feeding behaviours of cruiser fish by inertial and magnetic sensors

A method was developed and applied for monitoring two types of fast-start locomotion (feeding and escape) of a cruiser fish, Japanese amberjacks Seriola quinqueradiata. A data logger, which incorporated a 3-axis gyroscope, a 3-axis accelerometer and a 3-axis magnetometer, was attached to the five fish. The escape, feeding and routine movements of the fish, which were triggered in tank experiments, were then recorded by the data logger and video cameras. The locomotor variables, calculated based on the high resolution measurements by the data logger (500 Hz), were investigated to accurately detect and classify the types of fast-track behaviour. The results show that fast-start locomotion can be detected with a high precision (0.97) and recall rate (0.96) from the routine movements. Two types of fast-start movements were classified with high accuracy (0.84). Accuracy was greater if the data were obtained from the data logger, which combined an accelerometer, a gyroscope and a magnetometer, than if only an accelerometer (0.80) or a gyroscope (0.66) was used.

Fatty acid synthase as a factor required for exercise-induced cognitive enhancement and dentate gyrus cellular proliferation

Voluntary running is a robust inducer of adult hippocampal neurogenesis. Given that fatty acid synthase (FASN), the key enzyme for de novo fatty acid biosynthesis, is critically involved in proliferation of embryonic and adult neural stem cells, we hypothesized that FASN could mediate both exercise-induced cell proliferation in the subgranular zone (SGZ) of the dentate gyrus (DG) and enhancement of spatial learning and memory. In 20 week-old male mice, voluntary running-induced hippocampal-specific upregulation of FASN was accompanied also by hippocampal-specific accumulation of palmitate and stearate saturated fatty acids. In experiments addressing the functional role of FASN in our experimental model, chronic intracerebroventricular (i.c.v.) microinfusions of C75, an irreversible FASN inhibitor, and significantly impaired exercise-mediated improvements in spatial learning and memory in the Barnes maze. Unlike the vehicle-injected mice, the C75 group adopted a non-spatial serial escape strategy and displayed delayed escape latencies during acquisition and memory tests. Furthermore, pharmacologic blockade of FASN function with C75 resulted in a significant reduction, compared to vehicle treated controls, of the number of proliferative cells in the DG of running mice as measured by immunoreactive to Ki-67 in the SGZ. Taken together, our data suggest that FASN plays an important role in exercise-mediated cognitive enhancement, which might be associated to its role in modulating exercise-induced stimulation of neurogenesis.

FLZ alleviates the memory deficits in transgenic mouse model of Alzheimer's disease via decreasing beta-amyloid production and tau hyperphosphorylation

Alzheimer’s disease (AD) is the most common cause of dementia worldwide and mainly characterized by the aggregated β-amyloid (Aβ) and hyperphosphorylated tau. FLZ is a novel synthetic derivative of natural squamosamide and has been proved to improve memory deficits in dementia animal models. In this study, we aimed to investigate the mechanisms of FLZ’s neuroprotective effect in APP/PS1 double transgenic mice and SH-SY5Y (APPwt/swe) cells. The results showed that treatment with FLZ significantly improved the memory deficits of APP/PS1 transgenic mice and decreased apoptosis of SH-SY5Y (APPwt/swe) cells. FLZ markedly attenuated Aβ accumulation and tau phosphorylation both in vivo and in vitro. Mechanistic study showed that FLZ interfered APP processing, i.e., FLZ decreased β-amyloid precursor protein (APP) phosphorylation, APP-carboxy-terminal fragment (APP-CTF) production and β-amyloid precursor protein cleaving enzyme 1 (BACE1) expression. These results indicated that FLZ reduced Aβ production through inhibiting amyloidogenic pathway. The mechanistic study about FLZ’s inhibitory effect on tau phosphorylation revealed t the involvement of Akt/glycogen synthase kinase 3β (GSK3β) pathway. FLZ treatment increased Akt activity and inhibited GSK3β activity both in vivo and in vitro. The inhibitory effect of FLZ on GSK3β activity and tau phosphorylation was suppressed by inhibiting Akt activity, indicating that Akt/GSK3β pathway might be the possible mechanism involved in the inhibitory effect of FLZ on tau hyperphosphorylation. These results suggested FLZ might be a potential anti-AD drug as it not only reduced Aβ production via inhibition amyloidogenic APP processing pathway, but also attenuated tau hyperphosphoylation mediated by Akt/GSK3β.

Sex differences and similarities in the neuroendocrine regulation of social behavior in an African cichlid fish

An individual's position in a social hierarchy profoundly affects behavior and physiology through interactions with community members, yet little is known about how the brain contributes to status differences between and within the social states or sexes. We aimed to determine sex-specific attributes of social status by comparing circulating sex steroid hormones and neural gene expression of sex steroid receptors in dominant and subordinate male and female Astatotilapia burtoni, a highly social African cichlid fish. We found that testosterone and 17β-estradiol levels are higher in males regardless of status and dominant individuals regardless of sex. Progesterone was found to be higher in dominant individuals regardless of sex. Based on pharmacological manipulations in males and females, progesterone appears to be a common mechanism for promoting courtship in dominant individuals. We also examined expression of androgen receptors, estrogen receptor α, and the progesterone receptor in five brain regions that are important for social behavior. Most of the differences in brain sex steroid receptor expression were due to sex rather than status. Our results suggest that the parvocellular preoptic area is a core region for mediating sex differences through androgen and estrogen receptor expression, whereas the progesterone receptor may mediate sex and status behaviors in the putative homologs of the nucleus accumbens and ventromedial hypothalamus. Overall our results suggest sex differences and similarities in the regulation of social dominance by gonadal hormones and their receptors in the brain.

Ethanol fuel improves pitfall traps through rapid sinking and death of captured orthopterans

The choice of killing solutions for pitfall traps can influence sampling and is highly dependent on the objectives of each study. It is becoming increasingly common, however, and is more environmentally friendly, to use the same organisms to extract information for different kinds of studies. The killing solution should, therefore, be able to sample local active organisms, as well as maintain the integrity of their organs, tissues, and macromolecules. In a previous work, we showed that using ethanol fuel as a killing solution maintains the integrity of the specimens and enhances the Orthoptera richness and abundance of samples. In the current study, we evaluated two explanations for this pattern. We set up a field experiment to test whether ethanol fuel is attractive for orthopterans, and we investigated in the laboratory whether individuals of Gryllus sp. sink or die faster in ethanol fuel than in other killing solutions. Our results allowed us to refute the hypotheses of attraction caused by ethanol fuel and showed that the higher sampling efficiency of ethanol fuel is directly linked to the specimens sinking and dying faster than in other killing solutions. Thus, in addition to taxonomic, anatomical, and molecular studies, we recommend ethanol fuel for sampling organisms active in the litter in ecological studies.