Marked Behavior Research Articles

Induction of territorial dominance and subordination behaviors in laboratory mice.

Territorial behaviors comprise a set of coordinated actions and response patterns found across animal species that promote the exclusive access to resources. House mice are highly territorial with a subset of males consistently attacking and chasing competing males to expel them from their territories and performing urine marking behaviors to signal the extent of their territories. Natural variation in territorial behaviors within a mouse colony leads to the formation of dominance hierarchies in which subordinate males can reside within the territory of a dominant male. While the full repertoire of such territorial behaviors and hierarchies has been extensively studied in wild-derived mice in semi-natural enclosures, so far they have not been established in the smaller enclosures and with the genetically-defined laboratory strains required for the application of neural recording and manipulation methods. Here, we present a protocol to rapidly induce an extensive repertoire of territorial behaviors in pairs of laboratory mice in an enclosure compatible with tethered neurocircuit techniques, including a method for the simultaneous tracking of urine marking behavior in mouse pairs. Using this protocol we describe the emergence of robust dominant-subordinate hierarchies between pairs of CD1 outbred or CD1xB6 F1 hybrid mice, but unexpectedly not in C57BL/6 inbred animals. Our behavioral paradigm opens the door for neurocircuit studies of territorial behaviors and social hierarchy in the laboratory.

Different types of marking behavior observed in the wild during the breeding period of the common hamster (Cricetus cricetus, cricetidae, rodentia)

Different types of marking behavior observed in the wild during the breeding period of the common hamster (Cricetus cricetus, cricetidae, rodentia)

Abundance and Leishmania infection patterns of the sand fly Psathyromyia cratifer in Southern Mexico.

Localized cutaneous leishmaniasis (LCL) is a serious public health problem in Southern Mexico. Six species of Phlebotominae (Diptera: Psychodidae) have been found to be infected with Leishmania (Leishmania) mexicana, the causative agent of LCL in the region. However, little is known about the biology and potential participation of Psathyromyia cratifer in the Leishmania transmission cycle in Mexico, and the Americas. The present study provides evidence of temporal infection caused by Leishmania in Psathyromyia cratifer as well as data on its population dynamics in a LCL endemic area during the well-known transmission cycle of Leishmania in Southern Mexico. Individual specimens of Psathyromyia cratifer were collected in four sites over the course of five months (from November 2020 through March 2021) using animal-baited, human-baited, and light traps. The temporal activity pattern (month + hour) of Psathyromyia cratifer was assessed along with its relationship with environmental variables. Moreover, Leishmania DNA and blood meals were analyzed and detected in female sand flies. This evidenced an infection rate ranging from 8% to 83%, and the record of Homo sapiens and Ototylomys phyllotis as blood hosts of this sand fly species. High abundances of these sand flies in human-baited traps were recorded which revealed the marked anthropophilic behavior of Psathyromyia cratifer. As regards the transmission dynamics of the parasite within the region, it was observed that the potential highest epidemiological risk for Leishmania transmission by Psathyromyia cratifer occurred during the months of January and March. This is the first contribution ever made to both the population dynamic and the temporal Leishmania prevalence patterns in Psathyromyia cratifer. The resulting findings suggest that this sand fly specimen is the sixth potential vector of L. (L.) mexicana in Southern Mexico. Nonetheless, various biology, behavior, and ecology strands are yet to be addressed. The latter, to determine the role it plays in the transmission dynamics of the parasite within the region, and other areas of the country.

A distinct neuronal ensemble of prelimbic cortex mediates spontaneous pain in rats with peripheral inflammation

The absence of a comprehensive understanding of the neural basis of spontaneous pain limits the development of therapeutic strategies targeting this primary complaint of patients with chronic pain. Here we report a distinct neuronal ensemble within the prelimbic cortex which processes signals related to spontaneous pain in rats with chronic inflammatory pain. This neuronal ensemble specifically encodes spontaneous pain-related behaviors, independently of other locomotive and evoked behaviors. Activation of this neuronal ensemble elicits marked spontaneous pain-like behaviors and enhances nociceptive responses, whereas prolonged silencing of its activities alleviates spontaneous pain and promotes overall recovery from inflammatory pain. Notably, afferents from the primary somatosensory cortex and infralimbic cortex bidirectionally modulate the activities of the spontaneous pain-responsive prelimbic cortex neuronal ensemble and pain behaviors. These findings reveal the cortical basis of spontaneous pain at the neuronal level, highlighting a distinct neuronal ensemble within the prelimbic cortex and its associated pain-regulatory brain networks.

Male condition and seminal fluid affect female host-marking behavior in the Mexican fruit fly

Mating and the transfer of seminal fluid components including male accessory glands (MAGs) proteins can affect oviposition behavior in insects. After oviposition, some species of fruit flies deposit a host-marking pheromone (HMP) on the fruit that discourages oviposition by other females of the same or different species or genus and reduces competition between larvae. However, we know very little about how mating, receiving seminal fluid, or male condition can affect female host marking behavior. Here, we tested how the physiological state of females (mated or unmated), the receipt of seminal fluid, and the condition of the male (wild or sterile) affect oviposition and host-marking behavior (HMB) in Anastrepha ludens (Diptera: Tephritidae). We also determined the efficiency of the host-marking pheromone from mated or unmated females in deterring oviposition. In a further examination of how seminal fluid may be affecting HMB we assessed if there were differences in the size of wild or sterile MAGs and the protein quantity transferred during mating. Our results indicate that receiving seminal fluid increased egg laying and increased time invested in host-marking (HM). Unmated females laid fewer eggs than mated females but invested the same amount of time in depositing host-marking pheromone, which had similar effectiveness in deterring oviposition as that of mated females. Females that mated with sterile males laid the same number of eggs as females that mated with wild males but spent less time depositing host-marking pheromone, which suggests that females detect the condition of the male and invest less in marking hosts. Finally, sterile males had larger accessory glands and transferred more MAGs proteins during mating compared to wild males. Seminal proteins could be manipulating HM behavior and female investment into their current reproductive effort. We are only beginning to understand how male condition and seminal fluid can affect female physiology and maternal investment in HMP.

Use of latrines and territorial marking behaviors by Subulo gouazoubira in a remnant of the Atlantic Forest in southeastern Brazil

Use of latrines and territorial marking behaviors by Subulo gouazoubira in a remnant of the Atlantic Forest in southeastern Brazil

Transformational faulting in Mn2GeO4 from olivine to wadsleyite structure: Implications for physical mechanism of deep-focus earthquakes

High-pressure and temperature deformation experiments interfaced with acoustic emission (AE) monitoring have been conducted to study transformational faulting in Mn2GeO4 olivine, which transforms to the β phase, isostructural to wadsleyite. Metastable Mn2GeO4 olivine exhibits a marked embrittlement behavior at temperatures between 800 and 1100 K, emitting numerous AEs. At each temperature, brittle deformation is characterized by a two-stage process: (1) a “preparation” stage with numerous diffusedly located low-magnitude AEs and large b values (>2), and (2) a failure stage where larger-magnitude AEs form a planar distribution with b values about 1. Microstructure analysis reveals extensive kink band development in olivine grains in the recovered samples. Kink band boundaries (KBBs), with a typical thickness of ∼100 nm, are filled with a nanometric β-Mn2GeO4 “gouge”. A dense array of secondary shear localizations is often present within the kink bands, suggesting significant shear deformation therein. The combined observations suggest that faulting in metastable Mn2GeO4 olivine is a self-similar process, from grain-scale to the sample-scale. Both observed embrittlement behavior and the microstructure of metastable Mn2GeO4 olivine are essentially identical to those in Mg2GeO4 olivine we have reported previously, indicating that the physical mechanism of faulting in metastable olivine is insensitive to the specific crystallographic structure of the high-pressure phase. The low b values (about 1) observed in the faulting process in our experiments are similar to those of deep focus earthquakes in cold subduction zones. Our observed mechanism explains deep focus seismicity in cold metastable mantle wedges, provided that the self-similarity assumption holds to geological scales.

Маркування ведмедем (Ursus arctos) дерев у Чорнобильському біосферному заповіднику

For the first time in the Ukrainian Polissia and the Chornobyl Radiation and Ecological Biosphere Reserve (ChREBR), a concentrated linear distribution of bear-marked spruce trees was found at the abandoned estates of the village of Opachychi along the second terrace of the Prypiat River floodplain. Individual sightings of bears (Ursus arctos) in the Ukrainian Polissia have been known since the 1990s, but there are no reliable data on the reproduction of this species. The abundance of bears in Belarus has increased in recent years, which leads to the possibility of females coming to the Polissia from the north. Dried spruce trees without resin were not marked by the bear, and the animal moved on to live trees. Friction and more intensive marking of trees was recorded mainly in the eastern direction. Most of the marked spruce trees were upright with no branches to the height of the marking. The intensive marking behaviour of bears in 2023 in the ChREBR can be considered as the appearance of a female, as signalling to a female, and as a sign of dominance towards a male competitor. Two adult males were observed near one of the marked trees (data from amateurs). Special field surveys are needed to identify females with cubs to confirm or refute the hypothesis that the intensity of bear marking can be used in the event of the presence of a female bear in oestrus. Along the bear-marked trees in the village of Opachychi of the ChPEBR, an ecological trail and a visitor centre of large carnivores and herbivores should be created, which would be popular destinations. It is advisable to arrange a location for wildlife observations in an abandoned house for photo and video shooting, as is usually done in Sweden, Bulgaria, Romania, and Spain. In such tours, the effectiveness of the observation is not guaranteed and only preliminary statistics of wildlife encounters are provided. For this purpose, it is advisable to create two feeding areas for predatory mammals with dry food, as well as a salt marsh and a feeding trough for ungulates. The majority of the ChREBR territory has a low incidence of markings. The bear in the Polissia, as elsewhere in Europe, is expanding its range naturally, but at a slow pace due to the low intensity of female dispersal. Tree marking by bears was also observed in Chernihiv Oblast, in the Mizhrichynskyi Regional Landscape Park. It is advisable to release several bears in the ChEBR to create a reproductive centre for this species in the Polissia.

Seismic design-assisted-by-testing approach for racks with dissipative baseplates in the cross-aisle direction

A design-assisted-by-testing strategy is proposed for the upright frames of adjustable pallet racks. This methodology defines a procedure that aims to locate marked post-elastic behavior at the floor-to-upright connections of lateral resisting frames in the cross-aisle direction. Such connections are intended to enhance the performance of the cross-aisle frames when subjected to dynamic forces in their plane. The chosen baseplate connection is experimentally tested using monotonic and cyclic protocols at the Steel Structures Laboratory of the National Technical University of Athens (Greece). Then, a numerical model of the baseplate is calibrated using literature parameter definitions and hence validated using physical data. Additionally, the dynamic response of two upright frames is numerically investigated: one with traditional hinge connections and another with dissipative ones. This study indicates that the proposed procedure successfully enhances ductility, resulting in a significant reduction (up to 50%) in upright axial forces compared to the conventional configuration. Finally, the open-source code for ground motion selection, together with its database, is released.

ROS-responsive celastrol-nanomedicine alleviates inflammation for dry eye disease

Dry eye disease (DED) is a major global eye disease leading to severe eye discomfort and even vision impairment. The incidence of DED has been gradually increasing with the high frequency of use of electronic devices. It has been demonstrated that celastrol (Cel) has excellent therapeutic efficacy in ocular disorders. However, the poor water solubility and short half-life of Cel limit its further therapeutic applications. In this work, a reactive oxygen species (ROS) sensitive polymeric micelle was fabricated for Cel delivery. The micelles improve the solubility of Cel, and the resulting Cel loaded micelles exhibit an enhanced intervention effect for DED. The in vitro results demonstrated that Cel-nanomedicine had a marked ROS responsive release behavior. The results of in vitro and in vivo experiments demonstrated that Cel has excellent biological activities to alleviate inflammation in DED by inhibiting TLR4 signaling activation and reducing pro-inflammatory cytokine expression. Therefore, the Cel nanomedicine can effectively eliminate ocular inflammation, promote corneal epithelial repair, and restore the number of goblet cells and tear secretion, providing a new option for the treatment of DED.

Insights into marking behavior of giant anteaters: a camera trap study in the rupununi savannahs, Guyana

Abstract The Giant Anteater (Myrmecophaga tridactyla), facing threats from habitat degradation and hunting, remains a species of enigmatic behavior. This study analyzed camera trap data collected over 7700 camera trap nights in 49 stations near marked trees in Southern Guyana. A total of 883 Giant Anteater sightings were recorded, categorized into solitary adults (797), females with offspring (70), solitary juveniles (8), and paired adults (6). Meticulous observations documented various behaviors, distinguishing chemical (sniffing) and visual (scratching, climbing, hugging, rubbing) tree-marking from non-tree-marking behaviors (foraging, self-scratching, rolling, urinating/defecating). For solitary individual, a PCA revealed an inverse correlation between ignoring and sniffing (explaining 33.64 % of PC1), suggesting individuals engage in one behavior per observation. We observed an inverse correlation between hug/scratch/rub and climb (20.75 % of PC2). A weighted PCA assessing correlations by social categories, distinguishing marking behaviors from ignoring the tree (explaining 95.6 % of PC1). Scratching trees without climbing or hugging occurred from 3 pm to 1 am, with climbing most frequent between 8 and 10 pm. These behaviors were common during peak anteater sightings, peaking in May, with fewer observations in September. Overall, Giant Anteaters exhibit tree-marking behaviors, including scratching, climbing, and hugging and that a primary purpose for this behavior is communication.

Design Optimization of emulsions based on fine fraction of durum wheat oil cake: Structural and rheological properties

The production and stabilization of food-grade emulsions by using plant-derived particles have gained great attention due to the increasing demand for sustainable and plant-based alternatives. This study aims to explore the feasibility of using durum wheat oil and durum wheat oil cake, micronized and dry-fractioned (ff-DWOC), with no further chemical treatments, to produce emulsion gels. The emulsions obtained through a design of experiments (DoE) for mixture were analysed for their textural properties. The results of the textural parameters were subsequently modelled according to quadratic model. The nine emulsions were then characterized for their creaming index during 14 days of storage. The three most promising emulsions in terms of textural properties and creaming stability, were then characterized for their microstructure and rheological properties. The formulations with higher proportions of ff-DWOC and durum wheat oil affected the textural parameters, minimizing syneresis phenomena and serum phase separation, then resulting in excellent creaming stability over 14 days of storage. The emulsions containing 25% of ff-DWOC and 20 and 30% of oil displayed homogenous distribution of the oil droplets and a well-developed network, while emulsion with 15% ff-DWOC and 40% of oil (E7) showed a dense and compact continuous phase. According to the rheological results, the emulsions mentioned above exhibited a gel-like structures with G’ > G’‘. E7 had the highest G′ and G″ values, indicating a marked solid-like behaviour. These emulsions demonstrated compelling attributes, positioning them as strong contenders for incorporation into the food industry as innovative ingredients.

Size matters: Natural experiments suggest the dear enemy effect is moderated by pack size in African wild dogs.

Remote monitoring of communal marking sites, or latrines, provides a unique opportunity to observe undisturbed scent marking behaviour of African wild dogs (Lycaon pictus). We used remote camera trap observations in a natural experiment to test behavioural scent mark responses to rivals (either familiar neighbours or unfamiliar strangers), to determine whether wild dogs exhibit the "dear enemy" or "nasty neighbour" response. Given that larger groups of wild dogs represent a greater threat to smaller groups, including for established residents, we predicted that the overarching categories "dear enemy" vs. "nasty neighbour" may be confounded by varying social statuses that exists between individual dyads interacting. Using the number of overmarks as a metric, results revealed an interaction between sender and receiver group size irrespective of familiarity consistent with this prediction: in general, individuals from large resident packs overmarked large groups more than they overmarked smaller groups, whereas individuals from smaller packs avoided overmarking larger groups, possibly to avoid detection. Monitoring a natural system highlights variables such as pack size that may be either overlooked or controlled during scent presentation experiments, influencing our ability to gain insights into the factors determining territorial responses to rivals.

Home range in genus Capra: from polygons to Brownian bridges of scabietic and healthy Iberian ibexes (Capra pyrenaica).

Home range and home range overlap can be used to describe use of space and movement of wildlife. During the last years, advancements in technology have greatly improved our understanding of animal movement, especially among large herbivores. Wild ungulate abundance and distribution have increased in temperate areas. Moreover, their diseases-including sarcoptic mange in the Iberian Ibex (Capra pyrenaica)-have become a cause of concern for livestock, public health, and wildlife conservation. In this study, we first reviewed existing literature on the home range of species in the genus Capra. We then analyzed data from 52 GPS-GSM-collared Iberian ibexes, of which 33 were healthy and 19 were affected by sarcoptic mange from 3 different populations in the southeastern Iberian Peninsula to analyze: (1) differences in size and characteristics of home ranges obtained by the 3 most commonly used methodologies-minimum convex polygon, kernel density estimation, and Brownian bridges movement models (BBMMs); and (2) the impact of endemic sarcoptic mange on Iberian Ibex home range. The literature review revealed that available information on spatial behavior of Capra spp. was based only on 3 species, including the Iberian Ibex, estimated through a diversity of methods which made it difficult to compare results. We found positive correlations among the different home range estimation methods in the Iberian Ibex, with BBMMs proving to be the most accurate. This study is the first to use BBMMs for estimating home range in this species, and it revealed a marked seasonal behavior in spatial use, although sarcoptic mange smoothed such seasonal pattern. The seasonal overlaps obtained suggest that core areas of the Iberian Ibex change within wider home range areas, which are ecological parameters relevant to identifying key areas for species management and conservation.

Performance in Behavioral Testing in an Animal Model of Post-Surgical Hypoparathyroidism.

Hypoparathyroidism (HypoPT) is characterized by hypocalcemia and undetectable/inappropriately low PTH. Post-surgical HypoPT (PS-HypoPT) is the most common cause. Patients with PS-HypoPT present neuropsychological symptoms, probably due to the PTH deprivation in the central nervous system (CNS). However, these mechanisms are still not elucidated. The aim of this study was to evaluate the effects of PTH deprivation on CNS in an animal model of PS-HypoPT via a cognitive/behavioral assessment approach. A surgical rat model of PS-HypoPT was obtained and treated with calcium to maintain normocalcemia. Twenty PS-HypoPT rats and twenty sham-operated controls (Crl) underwent behavioral testing in a Morris Water Maze (MWM), Open Field (OF), and Elevated Plus Maze (EPM). In the MWM, PTx rats showed a higher Escape Latency Time compared to Crl rats (p < 0.05); we observed a statistically significant improvement in the performance (day 1 to 8 p < 0.001), which was less pronounced in PTx group. In the OF test, the time and distance spent in the zone of interest were significantly lower in the PTx group compared with the Crl (p < 0.01 and p < 0.01). In the EPM experiment, the time spent in the close arm was significantly higher in the PTx group compared with the Crl (p < 0.01). This animal model of PS-HypoPT shows an impairment in spatial memory, which improved after training, and a marked anxiety-like behavior, resembling the condition of patients with PS-HypoPT. Further studies are needed to elucidate mechanisms.

Multi-scale habitat modelling of latrine site selection by sympatric carnivores in an Albany Thicket landscape, South Africa

ContextUnderstanding how species select resources often requires assessing the environment at different spatial scales. Although the function of latrines in animal communication and social interactions has been studied in several carnivores, latrine site selection remains under-researched.ObjectivesWe aimed to describe the characteristics of latrines and determine the environmental factors, operating at different scales, that drive latrine site selection by two sympatric genet species (Genetta genetta and G. tigrina) in an Albany Thicket landscape (South Africa).MethodsWe used a multi-scale modelling framework to investigate latrine site selection by comparing environmental characteristics at used latrines with that of two random points at four different scales. We then adapted a match-control design to derive the probability of latrine site selection.ResultsAt the fine scale, genets selected latrine sites located in steeper slopes and boasting a higher availability of favourable micro-structures (e.g., burrows, termite mounds, hollow branches). At the landscape scale, latrines were positively associated with riverine forest corridors where they occurred in clusters. Genets avoided open areas and high terrain ruggedness to place their latrines. The best scale-independent model revealed the higher importance of edge habitats like riverine corridors and, to a lesser extent, dirt roads.ConclusionsThis study outlines the importance of including fine scale variables in multi-scale selection studies, as they may reveal features that are crucial for animal marking behaviour. Overall, our findings highlight the scales at which various factors influence latrine site selection the most. Based on our results, we suggest management practices that maintain animal communication by preserving riverine habitats across landscapes.

High-throughput sequencing and characterization of potentially pathogenic fungi from the vaginal mycobiome of giant panda (Ailuropoda melanoleuca) in estrus and non-estrus.

The giant panda (Ailuropoda melanoleuca) reproduction is of worldwide attention, and the vaginal microbiome is one of the most important factors affecting the reproductive rate of giant pandas. The aim of this study is to investigate the diversity of vaginal mycobiota structure, and potential pathogenic fungi in female giant pandas during estrus and non-estrus. This study combined with high-throughput sequencing and laboratory testing to compare the diversity of the vaginal mycobiota in giant pandas during estrus and non-estrus, and to investigate the presence of potentially pathogenic fungi. Potentially pathogenic fungi were studied in mice to explore their pathogenicity. The results revealed that during estrus, the vaginal secretions of giant pandas play a crucial role in fungal colonization. Moreover, the diversity of the vaginal mycobiota is reduced and specificity is enhanced. The abundance of Trichosporon and Cutaneotrichosporon in the vaginal mycobiota of giant pandas during estrus was significantly higher than that during non-estrus periods. Apiotrichum and Cutaneotrichosporon were considered the most important genera, and they primarily originate from the environment owing to marking behavior exhibited during the estrous period of giant pandas. Trichosporon is considered a resident mycobiota of the vagina and is an important pathogen that causes infection when immune system is suppressed. Potentially pathogenic fungi were further isolated and identified from the vaginal secretions of giant pandas during estrus, and seven strains of Apiotrichum (A. brassicae), one strain of Cutaneotrichosporon (C. moniliiforme), and nine strains of Trichosporon (two strains of T. asteroides, one strain of T. inkin, one strain of T. insectorum, and five strains of T. japonicum) were identified. Pathogenicity results showed that T. asteroides was the most pathogenic strain, as it is associated with extensive connective tissue replacement and inflammatory cell infiltration in both liver and kidney tissues. The results of this study improve our understanding of the diversity of the vaginal fungi present in giant pandas and will significantly contribute to improving the reproductive health of giant pandas in the future.

The Antidepressant Effect of Magnolol on Depression-Like Behavior of CORT-Treated Mice.

Although the antidepressant-like effect of magnolol has been revealed in previous reports, the mechanism remains unclear. In this study, the antidepressant-like effect of magnolol on corticosterone-induced (CORT-induced) mice was investigated in vivo. After 21 days of CORT induction, the mice showed marked depressive-like behaviors, with a decrease in sucrose preference score and an increase in immobility time in the tail suspension test (TST) and forced swimming test (FST). Pretreatment with either magnolol (50 mg/kg, i.p.) or the kappa opioid receptor (KOR) antagonist nor-BNI (10 mg/kg, i.p.) prevented CORT-induced depression-like behavior and reduced CORT-induced dynorphin (DYN A) elevation in the hippocampal ventral DG. However, no depression-like behavior was observed in mice with KOR downregulation in the ventral DG. We further found that upregulation of DYN A in the DG caused depression-like behavior, which was blocked by intraperitoneal injection of nor-BNI and modulated by magnolol. The present study demonstrated that magnolol could ameliorate CORT-induced depression-like behaviors, by modulating the DYN A/KOR system in the ventral DG of the hippocampus.

Divergent Acute and Enduring Changes in 50-kHz Ultrasonic Vocalizations in Rats Repeatedly Treated With Amphetamine and Dopaminergic Antagonists: New Insights on the Role of Dopamine in Calling Behavior.

Rats emit 50-kHz ultrasonic vocalizations (USVs) in response to nonpharmacological and pharmacological stimuli, with addictive psychostimulants being the most effective drugs that elicit calling behavior in rats. Earlier investigations found that dopamine D1-like and D2-like receptors modulate the emission of 50-kHz USVs stimulated in rats by the acute administration of addictive psychostimulants. Conversely, information is lacking on how dopamine D1-like and D2-like receptors modulate calling behavior in rats that are repeatedly treated with addictive psychostimulants. We evaluated the emission of 50-kHz USVs in rats repeatedly treated (×5 on alternate days) with amphetamine (1mg/kg, i.p.) either alone or together with (1) SCH 23390 (0.1-1mg/kg, s.c.), a dopamine D1 receptor antagonist; (2) raclopride (0.3-1mg/kg, s.c.), a selective dopamine D2 receptor antagonist; or (3) a combination of SCH 23390 and raclopride (0.1+0.3mg/kg, s.c.). Calling behavior of rats was recorded following pharmacological treatment, as well as in response to the presentation of amphetamine-paired cues and to amphetamine challenge (both performed 7 days after treatment discontinuation). Amphetamine-treated rats displayed a sensitized 50-kHz USV emission during repeated treatment, as well as marked calling behavior in response to amphetamine-paired cues and to amphetamine challenge. Antagonism of D1 or D2 receptors either significantly suppressed or attenuated the emission of 50-kHz USVs in amphetamine-treated rats, with a maximal effect after synergistic antagonism of both receptors. These results shed further light on how dopamine transmission modulates the emission of 50-kHz USVs in rats treated with psychoactive drugs.

Magnetic behaviour of a spin-canted asymmetric lanthanide quinolate trimer.

An asymmetrical dysprosium trimer with a molecular formula of [Dy3(hq)7(hqH)(NO3)2(H2O)] was obtained through a reflux reaction employing as starting material Dy(NO3)3·nH2O and 8-quinolinoline as ligand. Magnetic susceptibility investigations show the system to be an SMM, which was corroborated by sub-Kelvin μSQUID studies. Upon cooling, the magnetic susceptibility also exhibits a decrease in the χMT product, which was confirmed to be due to intramolecular antiferromagnetic interactions. μSQUID measurements, moreover, reveal a marked magnetic behaviour in the angular dependence of the hysteresis loops. The latter is a direct consequence of the non-colinear spin arrangement of the anisotropy axes of each Dy(III) ion in [Dy3(hq)7(hqH)(NO3)2(H2O)] and the interaction between the ions, as also evidenced by CASSCF calculations. Our results evidence the effect of spin canting along with the intramolecular interactions, which can induce non-trivial magnetic behaviour in SMMs.