SUMMARYFlagship species are among key marketing tools used by conservation organizations to motivate public support, but are often selected in an ad hoc, rather than systematic, manner. Furthermore, it is unclear whether selected flagship species do motivate public support. This paper describes a multi-method exploratory study, carried out in Switzerland, which aimed to determine the selection criteria for flagship species and measure whether a species selected according to these criteria was able to motivate support. Fourteen representatives of international, regional and local conservation organizations were interviewed and the selection criteria for their flagship species were identified. A charismatic species (the great spotted woodpecker) that meets these criteria and an apparently less charismatic species (the clover stem weevil) were selected as treatments in a quantitative experiment with 900 respondents. Using conjoint analysis, it was found that both charismatic and uncharismatic species have the ability to positively influence public preferences for habitat variables that encourage biodiversity in urban landscapes. These results may be used by conservation organizations to assist in the selection of flagship species, and in particular for flagship species that are intended to perform a specific conservation function.

Clinical and preclinical research with modulators at the -methyl-d-aspartate (NMDA) receptor GluN2B N-terminal domain (NTD) aims for the treatment of various neurologic diseases. The interpretation of the results is hampered by the lack of a suitable NMDA PET tracer for assessing the receptor occupancy of potential drugs. We have developedC-Me-NB1 as a PET tracer for imaging GluN1/GluN2B-containing NMDA receptors and used it to investigate in rats the dose-dependent receptor occupancy of eliprodil, a GluN2B NTD modulator. C-Me-NB1 was synthesized and characterized by in vitro displacement binding experiments with rat brain membranes, in vitro autoradiography, and blocking and displacement experiments by PET and PET kinetic modeling. Receptor occupancy by eliprodil was studied by PET withC-Me-NB1. C-Me-NB1 was synthesized at 290 ± 90 GBq/μmol molar activity, 7.4 ± 1.9 GBq total activity at the end of synthesis ( = 17), and more than 99% radiochemical purity. C-Me-NB1 binding in rat brain was blocked in vitro and in vivo by the NTD modulators Ro-25-6981 and eliprodil. Half-maximal receptor occupancy by eliprodil occurred at 1.5 μg/kg. At 1 mg/kg of eliprodil, a dose with reported neuroprotective effects, more than 99.5% of binding sites were occupied. In vitro,C-Me-NB1 binding was independent of the σ-1 receptor (Sigma1R), and the Sigma1R agonist (+)-pentazocine did not compete for high-affinity binding. In vivo, a 2.5 mg/kg dose of (+)-pentazocine abolished C-Me-NB1-specific binding, indicating an indirect effect of Sigma1R onC-Me-NB1 binding. C-Me-NB1 is suitable for the in vivo imaging of NMDA GluN1/GluN2B receptors and the assessment of receptor occupancy by NTD modulators. GluN1/GluN2B NMDA receptors are fully occupied at neuroprotective doses of eliprodil. Furthermore,C-Me-NB1 enables imaging of GluN1/GluN2B NMDA receptor cross talk.

The previously reported carbon-11 labeled GluN2B PET radioligand C-Me-NB1 served as a starting point for derivatization and led to the successful development of a radiofluorinated analogue designated (R)-F-OF-Me-NB1. Given the short physical half-life of 20.3 min for carbon-11, (R)-F-OF-Me-NB1 with a physical half-life of 109.8 min would allow satellite distribution to nuclear medicine facilities without an on-site cyclotron. Two fluorinated Me-NB1 derivatives, OF-Me-NB1 and PF-Me-NB1, were synthesized. Upon chiral resolution, the respective enantiomers were radiolabeled with carbon-11 and assessed in a proof-of-concept study by applying in vitro autoradiography on rodent brain sections. Based on the autoradiograms, (R)-OF-Me-NB1 was selected for radiofluorination and preclinical evaluation by ex vivo autoradiography, PET imaging, biodistribution and metabolite studies in Wistar rats. To rule out off-target binding to the σ1 receptor, the brain uptake of (R)-F-OF-Me-NB1 in wild-type mice was compared with σ1 receptor knock-out mice. Autoradiographic assessment revealed that both enantiomers ofC-PF-Me-NB1 distributed homogenously across all brain regions on rodent brain sections. In contrast, the two enantiomers of C-OF-Me-NB1 exhibited an entirely different behaviour. While (S)-C-OF-Me-NB1 bound virtually to all brain regions with considerable σ1 receptor binding, (R)-C-OF-Me-NB1 exhibited high selectivity and specificity for the GluN2B-rich rat forebrain. These findings were confirmed for the radiofluorinated analogue (R)-C-OF-Me-NB1, which was obtained via copper-mediated radiofluorination in radiochemical yields of 13-25% and molar activities ranging from 61-168 GBq/µmol. PET imaging and biodistribution studies in Wistar rats indicated appropriate pharmacokinetic profile and high in vivo specific binding of (R)-F-OF-Me-NB1 as revealed by blocking studies with GluN2B-antagonist CP101,606. Off-target binding to the σ1 receptor was excluded by PET imaging with σ1 receptor knock-out mice. Receptor occupancy experiments with CP101,606 revealed a D50-value of 8.3 µmol/kg (intravenous). (R)-F-OF-Me-NB1 is a promising radiofluorinated probe that exhibits specificity and selectivity for the GluN2B-containing N-methyl-D-aspartate (NMDA) complex and enables in vivo target occupancy studies in rodents.

Large neutral L-amino acids are substrates of system L amino acid transporters. The level of one of these, LAT1, is increased in many tumors. Aromatic L-amino acids may also be substrates of aromatic L-amino acid decarboxylase (AADC), the level of which is enhanced in endocrine tumors. Increased amino acid uptake and subsequent decarboxylation result in the intracellular accumulation of the amino acid and its decarboxylation product. 18 F-and 11 C-labeled neutral aromatic amino acids, such as L-3,4-dihydroxy-6-18 F-fluorophenylalanine ( 18 F-FDOPA) and 5-hydroxy-L-[b-11 C]tryptophan, are thus successfully used in PET to image endocrine tumors. However, 5-hydroxy-L-[b-11 C]tryptophan has a relatively short physical half-life (20 min). In this work, we evaluated the in vitro and in vivo characteristics of the 18 F-labeled tryptophan analog 5-(2-18 F-fluoroethoxy)-L-tryptophan ( 18 F-L-FEHTP) as a PET probe for tumor imaging. Methods: 18 F-L-FEHTP was synthesized by no-carrier-added 18 F fluorination of 5-hydroxy-L-tryptophan. In vitro cell uptake and efflux of 18 F-L-FEHTP and 18 F-FDOPA were studied with NCI-H69 endocrine small cell lung cancer cells, PC-3 pseudoendocrine prostate cancer cells, and MDA-MB-231 exocrine breast cancer cells. Small-animal PET was performed with the respective xenograft-bearing mice. Tissues were analyzed for potential metabolites. Results: 18 F-L-FEHTP specific activity and radiochemical purity were 50-150 GBq/mmol and greater than 95%, respectively. In vitro cell uptake of 18 F-L-FEHTP was between 48% and 113% of added radioactivity per milligram of protein within 60 min at 37°C and was blocked by greater than 95% in all tested cell lines by the LAT1/2 inhibitor 2-amino-2-norboranecarboxylic acid. 18 F-FDOPA uptake ranged from 26% to 53%/mg. PET studies revealed similar xenograft-to-reference tissue ratios for 18 F-L-FEHTP and 18 F-FDOPA at 30-45 min after injection. In contrast to the 18 F-FDOPA PET results, pretreatment with the AADC inhibitor S-carbidopa did not affect the 18 F-L-FEHTP PET results. No decarboxylation products of 18 F-L-FEHTP were detected in the xenograft homogenates. Conclusion: 18 F-L-FEHTP accumulates in endocrine and nonendocrine tumor models via LAT1 transport but is not decarboxylated by AADC. 18 F-L-FEHTP may thus serve as a PET probe for tumor imaging and quantification of tumor LAT1 activity. These findings are of interest in view of the ongoing evaluation of LAT1 substrates and inhibitors for cancer therapy.

Despite the broad implications of the cannabinoid type 2 receptor (CB2) in neuroinflammatory processes, a suitable CB2-targeted probe is currently lacking in clinical routine. In this work, we synthesized 15 fluorinated pyridine derivatives and tested their binding affinities toward CB2 and CB1. With a sub-nanomolar affinity (K i for CB2) of 0.8 nM and a remarkable selectivity factor of >12,000 over CB1, RoSMA-18-d 6 exhibited outstanding in vitro performance characteristics and was radiofluorinated with an average radiochemical yield of 10.6 ± 3.8% (n = 16) and molar activities ranging from 52 to 65 GBq/μmol (radiochemical purity > 99%). [18F]­RoSMA-18-d 6 showed exceptional CB2 attributes as demonstrated by in vitro autoradiography, ex vivo biodistribution, and positron emission tomography (PET). Further, [18F]­RoSMA-18-d 6 was used to detect CB2 upregulation on postmortem human ALS spinal cord tissues. Overall, these results suggest that [18F]­RoSMA-18-d 6 is a promising CB2 PET radioligand for clinical translation.

The study aims to investigate the performance characteristics of the enantiomers of 11 C-Me-NB1, a recently reported PET imaging probe that targets the GluN2B subunit of N-methyl-D-aspartate (NMDA) receptors. Methods: Reference compound Me-NB1 (inhibition constant for hGluN1/GluN2B, 5.4 nM) and the phenolic precursor were prepared via multistep synthesis. Following chiral resolution by high-performance liquid chromatography, enantiopure precursor compounds, (R)-NB1 and (S)-NB1, were labeled with 11 C and validated in rodents using in vitro/ex vivo autoradiography, PET experiments, and dose-response studies. To illustrate the translational relevance, (R)-11 C-Me-NB1 was validated in autoradiographic studies using postmortem human GluN2B-rich cortical and GluN2B-deficient cerebellar brain slices. To determine target engagement, receptor occupancy was assessed at different plasma concentrations of CP101,606, a GluN2B receptor antagonist. Results: The radiosynthesis of (R)-and (S)-11 C-Me-NB1 was accomplished in 42% ± 9% (decay-corrected) radiochemical yields. Molar activity ranged from 40 to 336 GBq/μmol, and an excellent radiochemical purity of greater than 99% was achieved. Although (R)-11 C-Me-NB1 displayed heterogeneous accumulation with high selectivity for the GluN2B-rich forebrain, (S)-11 C-Me-NB1 revealed a homogeneous distribution across all brain regions in rodent brain autoradiograms and predominantly exhibited σ 1 -receptor binding. Similar to rodent brain, (R)-11 C-Me-NB1 showed in postmortem human brain tissues higher binding in the cortex than in the cerebellum. Coincubation of the GluN2B-antagonist CERC-301 (1 μM) reduced cortical but not cerebellar binding, demonstrating the specificity of (R)-11 C-Me-NB1 binding to the human GluN2B-containing NMDA receptor. In vivo specificity of (R)-11 C-Me-NB1 in the GluN2B-expressing cortex, striatum, thalamus, and hippocampus was demonstrated by PET imaging in rodents. Applying GluN2B-antagonist eliprodil, an evident dose-response behavior was observed with (R)-11 C-Me-NB1 but not with (S)-11 C-Me-NB1. Our findings further underline the tightrope walk between GluN2B-and σ 1 -receptor-targeted imaging, illustrated by the entirely different receptor binding behavior of the 2 radioligand enantiomers. Conclusion: (R)-11 C-Me-NB1 is a highly selective and specific PET radioligand for imaging the GluN2B subunit of the NMDA receptor. The entirely different receptor binding behavior of (R)-11 C-Me-NB1 and (S)-11 C-Me-NB1 raises awareness of a delicate balance that is underlying the selective targeting of either GluN2Bcarrying NMDA or σ 1 -receptors.

a b s t r a c tIn the Amazon region diurnal line-transect census is the technique used by most monitoring programs to collect data on medium and large terrestrial mammals. However, this method usually fails to provide high quality information (e.g. abundance, occurrence) for some species, especially for larger bodied and less abundant ones, which are mostly threatened by human disturbances. Aiming to provide guidelines for monitoring programs in the region we compared the efficiency of three field techniques: (1) diurnal surveys (i.e. diurnal line-transect census with sign surveys), (2) nocturnal surveys and (3) camera trapping in non-flooded and seasonally flooded forest sites at the Uacari Sustainable Development Reserve, western Brazilian Amazonia. Nocturnal surveys provided poor information for all species, except pacas. Tracks accounted for 50% of the observations recorded during diurnal surveys, the most effective technique for smaller diurnal species and ungulates. For armadillos and rare species camera trapping was the most effective technique. Moreover, all techniques failed to detect the most common species, agouti, in at least two sites. High sampling effort using a combination of sampling methods and statistical analyses that enable the integration of different source data, such as photos, tracks and visual sightings, are necessary steps to maximize the efficiency of medium and large mammals monitoring programs in Amazonian forests.

Over the past century, human activities and their side effects have significantly threatened both ecosystems and resident species. Nevertheless, the genetic patterns of large felids that depend heavily on large and well-conserved continuous habitat remain poorly studied. Using the largest-ever contemporary genetic survey of wild jaguars (Panthera onca), we evaluated their genetic diversity and population structure in natural (Brazilian Amazon) and highly modified habitats (e.g. Cerrado, Caatinga) including those close to the northern (Yucatan, Mexico) and southern (Pantanal) edge of the species' distribution range. Data from our set of microsatellites revealed a pronounced genetic structure, with four genetically differentiated geographic areas. Geographic distance was not the only factor influencing genetic differentiation through the jaguar range. Instead, we found evidence of the effects of habitat deterioration on genetic patterns: while the levels of genetic diversity in the Amazon forest, the largest continuum habitat for the species, are high and consistent with panmixia across large distances, genetic diversity near the edge of the species distribution has been reduced through population contractions. Mexican jaguar populations were highly differentiated from those in Brazil and genetically depauperated. An isolated population from the Caatinga showed the genetic effects of a recent demographic decline (within the last 20-30 years), which may reflect recent habitat degradation in the region. Our results demonstrate that the jaguar is highly sensitive to habitat fragmentation especially in human-dominated landscapes, and that in Brazil, the existing but limited genetic connectivity in the central protected areas should be maintained. These conclusions have important implications for the management of wide-ranging species with high dispersal and low population density. The restoration of ecological connectivity between populations over relatively large scales should be one of the main priorities for species conservation.