Natural or Artificial? Habitat-Use by the Bull Shark, Carcharhinus leucas

BACKGROUND: Despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. We present the first direct comparison of the use of natural versus artificial habitats for the bull shark, Carcharhinus leucas, an IUCN ‘Near-threatened’ species - one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults. Understanding the value of alternate artificial coastal habitats to the lifecycle of the bull shark is crucial for determining the impact of coastal development on this threatened but potentially dangerous species. METHODOLOGY/FINDINGS: We used longline surveys and long-term passive acoustic tracking of neonate and juvenile bull sharks to determine the ontogenetic value of natural and artificial habitats to bull sharks associated with the Nerang River and adjoining canals on the Gold Coast, Australia. Long-term movements of tagged sharks suggested a preference for the natural river over artificial habitat (canals). Neonates and juveniles spent the majority of their time in the upper tidal reaches of the Nerang River and undertook excursions into adjoining canals. Larger bull sharks ranged further and frequented the canals closer to the river mouth. CONCLUSIONS/SIGNIFICANCE: Our work suggests with increased destruction of natural habitats, artificial coastal habitat may become increasingly important to large juvenile bull sharks with associated risk of attack on humans. In this system, neonate and juvenile bull sharks utilised the natural and artificial habitats, but the latter was not the preferred habitat of neonates. The upper reaches of tidal rivers, often under significant modification pressure, serve as nursery sites for neonates. Analogous studies are needed in similar systems elsewhere to assess the spatial and temporal generality of this research

Targeting the Oxytocin System: New Pharmacotherapeutic Approaches

Deficits in social behavioral domains, such as interpersonal communication, emotion recognition, and empathy, are a characteristic symptom in several neuropsychiatric disorders, including schizophrenia and autism spectrum disorder (ASD). The neuropeptide oxytocin (OT) has emerged as a key regulator of diverse social behaviors in vertebrates and, thus, has been identified as a potential therapeutic target for improving social dysfunction. In recent years, the field of OT research has seen an explosion of scientific inquiry, producing a more comprehensive picture of oxytocinergic signaling and the pathways that regulate its release and degradation in the brain. In this review, we provide an analysis of how this information is being exploited to accelerate the discovery of novel oxytocinergic therapeutics

Conformationally rigid derivatives of WAY-267,464: Synthesis and pharmacology at the human oxytocin and vasopressin-1a receptors

WAY-267,464 (1) and twelve conformationally rigid analogues (3a-f–4a-f) were synthesised, characterised and evaluated in cellular assays with the aim of systematically exploring interactions with the oxytocin receptor (OTR). Each analogue was evaluated in radioligand binding displacement assays at both human OTR and arginine vasopressin 1a receptors (V1aR). Physiological characterisation was determined by whole cell IP1 accumulation assays on stably transfected human embryonic kidney (HEK) cells. Incorporation of the rigid, optionally substituted benzene ring abolished OTR activity and diminished V1aR pharmacology when compared to 1. A general trend was observed in V1aR affinity for the propyl analogues (3d-3f) which identified the ortho-substituted analogue as the best in series (Ki = 251 nM) followed by a decrease in affinity through the meta and para-derivatives (3e; Ki = 874 nM and 3f; Ki = 1756 nM respectively). This study confirms the importance of the central pharmacophoric motifs of WAY-267,464 and illuminates the differences in the binding pocket of the highly conserved OTR and V1aR

Reversing binding sensitivity to A147T translocator protein

The translocator protein (TSPO) is a target for the development of neuroinflammation imaging agents. Clinical translation of TSPO PET ligands, such as [11C]DPA-713, has been hampered by the presence of a common polymorphism (A147T TSPO), at which all second-generation TSPO ligands lose affinity. Little is known about what drives binding at A147T compared to WT TSPO. This study aimed to identify moieties in DPA-713, and related derivatives, that influence binding at A147T compared to WT TSPO. We found changes to the nitrogen position and number in the heterocyclic core influences affinity to WT and A147T to a similar degree. Hydrogen bonding groups in molecules with an indole core improve binding at A147T compared to WT, a strategy that generated compounds that possess up to ten-times greater affinity for A147T. These results should inform the future design of compounds that bind both A147T and WT TSPO for use in neuroinflammation imaging

Leaf litter breakdown along an elevational gradient in Australian alpine streams

The breakdown of allochthonous organic matter, is a central step in nutrient cycling in stream ecosystems. There is concern that increased temperatures from climate change will alter the breakdown rate of organic matter, with important consequences for the ecosystem functioning of alpine streams. This study investigated the rate of leaf litter breakdown and how temperature and other factors such as microbial and invertebrate activities influenced this over elevational and temporal gradients. Dried leaves of Snow Gum (Eucalyptus pauciflora) and cotton strips were deployed in coarse (6 mm), and fine (50 mu m) mesh size bags along an 820 m elevation gradient. Loss of mass in leaf litter and cotton tensile strength per day (k per day), fungal biomass measured as ergosterol concentration, invertebrate colonization of leaf litter, and benthic organic matter (mass and composition) were determined. Both microbial and macroinvertebrate activities were equally important in leaf litter breakdown with the abundance of shredder invertebrate taxa. The overall leaf litter breakdown rate and loss of tensile strength in cotton strips (both k per day) were greater during warmer deployment periods and at lower elevations, with significant positive relationships between mean water temperature and leaf breakdown and loss of tensile strength rate, but no differences between sites, after accounting for the effects of temperature. Despite considerably lower amounts of benthic organic matter in streams above the tree line relative to those below, shredders were present in coarse mesh bags at all sites. Ergosterol concentration was greater on leaves in coarse mesh bags than in fine mesh bags, implying differences in the microbial communities. The importance of water temperatures on the rate of leaf litter breakdown suggests the potential effects of climate change-induced temperature increases on ecological processes in such streams

Reef-fidelity and migration of tiger sharks, Galeocerdo cuvier, across the Coral Sea

© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 9 (2014): e83249, doi:10.1371/journal.pone.0083249.Knowledge of the habitat use and migration patterns of large sharks is important for assessing the effectiveness of large predator Marine Protected Areas (MPAs), vulnerability to fisheries and environmental influences, and management of shark–human interactions. Here we compare movement, reef-fidelity, and ocean migration for tiger sharks, Galeocerdo cuvier, across the Coral Sea, with an emphasis on New Caledonia. Thirty-three tiger sharks (1.54 to 3.9 m total length) were tagged with passive acoustic transmitters and their localised movements monitored on receiver arrays in New Caledonia, the Chesterfield and Lord Howe Islands in the Coral Sea, and the east coast of Queensland, Australia. Satellite tags were also used to determine habitat use and movements among habitats across the Coral Sea. Sub-adults and one male adult tiger shark displayed year-round residency in the Chesterfields with two females tagged in the Chesterfields and detected on the Great Barrier Reef, Australia, after 591 and 842 days respectively. In coastal barrier reefs, tiger sharks were transient at acoustic arrays and each individual demonstrated a unique pattern of occurrence. From 2009 to 2013, fourteen sharks with satellite and acoustic tags undertook wide-ranging movements up to 1114 km across the Coral Sea with eight detected back on acoustic arrays up to 405 days after being tagged. Tiger sharks dove 1136 m and utilised three-dimensional activity spaces averaged at 2360 km3. The Chesterfield Islands appear to be important habitat for sub-adults and adult male tiger sharks. Management strategies need to consider the wide-ranging movements of large (sub-adult and adult) male and female tiger sharks at the individual level, whereas fidelity to specific coastal reefs may be consistent across groups of individuals. Coastal barrier reef MPAs, however, only afford brief protection for large tiger sharks, therefore determining the importance of other oceanic Coral Sea reefs should be a priority for future research.Funding was provided by the the Agence Francaise de Développement (http://www.afd.fr), French Pacific Fund, the CRISP program (www.crisponline.info) and QLD Fisheries

The role of polycyclic frameworks in modulating P2X<inf>7</inf> receptor function

Herein we describe our recent attempts to target the P2X7 receptor for potential treatment of neurological disorders. This work focusses on different polycycles including carborane, adamantane or cubane, joined by either a cyanoguanidine or an amide linker to phenyl or isoquinoline moieties. We have demonstrated the superiority of the adamantyl moiety over other polycycles in terms of synthetic accessibility and biological (cellular) activity. We have also shown that an amide or cyanoguanidine linker can greatly alter the biological activity of compounds. This SAR study provides important insights into the types of functionality required to target the P2X7 receptor

A Pilot Study with a Novel Setup for Collaborative Play of the Humanoid Robot KASPAR with children with autism

This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.This article describes a pilot study in which a novel experimental setup, involving an autonomous humanoid robot, KASPAR, participating in a collaborative, dyadic video game, was implemented and tested with children with autism, all of whom had impairments in playing socially and communicating with others. The children alternated between playing the collaborative video game with a neurotypical adult and playing the same game with the humanoid robot, being exposed to each condition twice. The equipment and experimental setup were designed to observe whether the children would engage in more collaborative behaviours while playing the video game and interacting with the adult than performing the same activities with the humanoid robot. The article describes the development of the experimental setup and its first evaluation in a small-scale exploratory pilot study. The purpose of the study was to gain experience with the operational limits of the robot as well as the dyadic video game, to determine what changes should be made to the systems, and to gain experience with analyzing the data from this study in order to conduct a more extensive evaluation in the future. Based on our observations of the childrens’ experiences in playing the cooperative game, we determined that while the children enjoyed both playing the game and interacting with the robot, the game should be made simpler to play as well as more explicitly collaborative in its mechanics. Also, the robot should be more explicit in its speech as well as more structured in its interactions. Results show that the children found the activity to be more entertaining, appeared more engaged in playing, and displayed better collaborative behaviours with their partners (For the purposes of this article, ‘partner’ refers to the human/robotic agent which interacts with the children with autism. We are not using the term’s other meanings that refer to specific relationships or emotional involvement between two individuals.) in the second sessions of playing with human adults than during their first sessions. One way of explaining these findings is that the children’s intermediary play session with the humanoid robot impacted their subsequent play session with the human adult. However, another longer and more thorough study would have to be conducted in order to better re-interpret these findings. Furthermore, although the children with autism were more interested in and entertained by the robotic partner, the children showed more examples of collaborative play and cooperation while playing with the human adult.Peer reviewe

Tricyclic heterocycles display diverse sensitivity to the A147T TSPO polymorphism

The 18 kDa translocator protein (TSPO) is a target for the development of imaging agents to detect neuroinflammation. The clinical utility of second-generation TSPO ligands has been hindered by the presence of a polymorphism, rs6971, which causes a non-conservative substitution of alanine for threonine at amino acid residue 147 (TSPO A147T). Given the complex nature of TSPO binding, and the lack of non-discriminating high-affinity ligands at both wild type and A147T forms of TSPO, a series of novel TSPO ligands containing various heterocyclic scaffolds was developed to explore the pharmacophoric drivers of affinity loss at TSPO A147T. In general, N-benzyl-N-methyl-substituted amide ligands showed increased affinity at TSPO A147T, and a pyrazolopyrimidine acetamide containing this motif displayed low nanomolar binding affinities to both TSPO forms

Reasons to not correct for leaching in TBI; Reply to Lind et al. (2022)

We believe that correcting for leaching in (terrestrial) litterbags studies such as the Tea Bag Index will result in more uncertainties than it resolves. This is mainly because leaching occurs in pulses upon changes in the environment and because leached material can still be mineralized after leaching. Furthermore, amount of material that potentially leaches from tea is comparable to other litter types. When correcting for leaching, it is key to be specific about the employed method, just like being specific about the study specific definition of decomposition