Reliability of the empathy selection task, a novel behavioral measure of empathy avoidance.

The empathy selection task is a novel behavioral paradigm designed to assess an individual's willingness to engage in empathy. Work with this task has demonstrated that people prefer to avoid empathy when some other activity is available, though individual differences that might predict performance on this task have been largely unexamined. Here, we assess the suitability of the empathy selection task for use in individual difference and experimental research by examining its reliability within and across testing sessions. We compare the reliability of summary scores on the empathy selection task (i.e., proportion of empathy choices) as an individual difference metric to that of two commonly used experimental tasks, the Stroop error rate and go/no-go commission rate. Next, we assess systematic changes at the item/trial level using generalized multilevel modeling which considers participants' individual performance variation. Across two samples (N = 89), we find that the empathy selection task is stable between testing sessions and has good/substantial test-retest reliability (ICCs = .65 and .67), suggesting that it is comparable or superior to other commonly used experimental tasks with respect to its ability to consistently rank individuals.

Zoo-housed mammals do not avoid giving birth on weekends.

There is evidence that zoo visitor presence can influence the behaviour and, in some cases, adrenal response of zoo animals, and can sometimes compromise animal welfare. In some laboratory studies, significantly more primate births have been reported on weekends, when fewer people are working there, compared with weekdays when staffing levels are at their highest. Here, we investigate whether there is evidence of a "weekend effect" on births in zoo animals as a result of visitor numbers. Unlike laboratories, zoos are typically busier with visitors on weekends than on weekdays, although staffing levels remain fairly consistent across days of the week. If zoo animal parturition is sensitive to human presence, then fewer births would be expected on weekends compared with weekdays. We tested this using birth data and visitor numbers on the entrance gate from zoo records across 16 species representing artiodactyls, perissodactyls, carnivores and primates at four British zoos, to see whether there is an association between mean daily birth rates and average visitor numbers. We predict that, if there is a visitor effect, daily births should be lower on weekends than weekdays and should correlate with mean daily visitor numbers. Results showed that births for all 16 species were randomly distributed through the week, and there was no significant decline in births on weekends. We conclude that the "weekend effect", if such a thing exists, does not appear to be a feature of zoo births, suggesting that elevated weekend visitor numbers are not sufficiently stressful to trigger delayed parturition.

RISK FACTORS ASSOCIATED WITH YOLK SAC RETENTION IN CAPTIVE-BRED HUMBOLDT PENGUIN (SPHENISCUS HUMBOLDTI) CHICKS.

Multiple occurrences of yolk sac retention prompted a retrospective investigation in a recently formed colony of captive Humboldt penguins (Spheniscus humboldti). Necropsy reports of 141 parent-reared penguin chicks that died between January 2014 and December 2018 were reviewed for evidence of yolk sac retention, defined as the presence of a yolk sac at postmortem examination of a chick aged 7 d or greater, and analyzed by demographic and pathological variables for identification of risk factors. Fifty-nine (65%) chicks that died at age 7 d or greater had a retained yolk sac at postmortem examination, revealing that this was a common condition in penguins in this population. Chicks that retained their yolk sac were also more likely to present with minimal gut contents (P = 0.02), have a prominent bursa of Fabricius (P < 0.01), and be the first chick hatched of their clutch (P = 0.02). Parental experience and age were not predictive of yolk sac retention, but there was a trend for chicks with retained yolk sacs to present with a poorer body condition, reduced weight, and reduced crown-rump length compared to chicks without a retained yolk sac. Histopathological and bacteriological findings of retained yolk sacs were not significantly different from those of chicks under 7 d of age. Although likely to be multifactorial, the association between yolk sac retention and indicators of suboptimal feed intake and growth (empty gastrointestinal tract, poor body condition score, decreased crown-rump length, and decreased weight at death) is hypothesized to be a result of parental neglect, leading to starvation and absorption arrest of the yolk, as previously indicated in broiler chicks.

The effect of visitors on the behavior of zoo-housed western lowland gorillas (Gorilla gorilla gorilla).

Primates, especially apes, are popular with the public, often attracting large crowds. These crowds could cause behavioral change in captive primates, whether positive, neutral, or negative. We examined the impact of visitors on the behavior of six western lowland gorillas (Gorilla gorilla gorilla), observing the troop over 6 weeks during high season (4.5 hr/day, 35 days, May-July 2016). We used focal scan sampling to determine activity budget and enclosure usage, and focal continuous sampling to identify bouts of anxiety-related behavior (visitor-directed vigilance, self-scratching, and aggression). Both daily zoo-entry numbers (VGATE ) and instantaneous crowds at the exhibit (VDENSITY ) were measured. Overall, VGATE had little effect across behaviors. However, consistent with the more acute time frame of measurement, VDENSITY was a better predictor of behavior; at high crowd volumes, we observed significant group-level changes in activity budget (increased inactivity, increased locomotion, and decreased environment-related behaviors), increase in some anxiety-related behaviors, and decreased enclosure usage. Although contributing similar effects, it could not be determined if crowd numbers, composition, or noise most affected the troop, nor any chronic effects of exposure to large crowds. Nevertheless, our findings suggest that measures to minimize the impacts of large crowds at the exhibit would be beneficial. Furthermore, we highlight potential discrepancies between common methods for measuring visitor numbers: VGATE is less sensitive to detecting visitor effects on behavioral indices than VDENSITY . Future studies should appropriately match the biological time frame of welfare indicators and visitor measures used to ensure the reliability of findings.

Diabetic hyperglycaemia activates CaMKII and arrhythmias by O-linked glycosylation.

Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is an enzyme with important regulatory functions in the heart and brain, and its chronic activation can be pathological. CaMKII activation is seen in heart failure, and can directly induce pathological changes in ion channels, Ca(2+) handling and gene transcription. Here, in human, rat and mouse, we identify a novel mechanism linking CaMKII and hyperglycaemic signalling in diabetes mellitus, which is a key risk factor for heart and neurodegenerative diseases. Acute hyperglycaemia causes covalent modification of CaMKII by O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAc modification of CaMKII at Ser 279 activates CaMKII autonomously, creating molecular memory even after Ca(2+) concentration declines. O-GlcNAc-modified CaMKII is increased in the heart and brain of diabetic humans and rats. In cardiomyocytes, increased glucose concentration significantly enhances CaMKII-dependent activation of spontaneous sarcoplasmic reticulum Ca(2+) release events that can contribute to cardiac mechanical dysfunction and arrhythmias. These effects were prevented by pharmacological inhibition of O-GlcNAc signalling or genetic ablation of CaMKIIδ. In intact perfused hearts, arrhythmias were aggravated by increased glucose concentration through O-GlcNAc- and CaMKII-dependent pathways. In diabetic animals, acute blockade of O-GlcNAc inhibited arrhythmogenesis. Thus, O-GlcNAc modification of CaMKII is a novel signalling event in pathways that may contribute critically to cardiac and neuronal pathophysiology in diabetes and other diseases.

Hungry for more: key stakeholders' support for more stringent school food policies.

OBJECTIVE: School food policies are an important component of comprehensive strategies to address child obesity and improve children's health. Evaluations have demonstrated that these policies can be initially well accepted and appropriately implemented, however little is known about how acceptance levels may change over time. The present study aimed to re-evaluate a school food policy 10 years after its introduction to assess key stakeholders' support for various policy extensions that would strengthen the scope of the policy. DESIGN: Online surveys administered 1 year after policy introduction (n 607, 2008) and 10 years after policy introduction (n 307, 2016). SETTING: Western Australia.ParticipantsSchool principals, teachers, canteen managers and presidents of parents & citizens associations from Western Australian Government primary schools. RESULTS: At both time points, and especially at time 2 (10 years post policy implementation), high levels of support were reported for the policy and possible policy extensions. Support was strongest for an additional requirement to integrate the canteen menu with the classroom health curriculum. CONCLUSIONS: The results suggest that once a policy has become embedded into school practices, stakeholders may be receptive to modifications that strengthen the policy to enhance its potential effects on children's diets.

Objective assessment of compliance with a state-wide school food-service policy via menu audits.

OBJECTIVE: The Healthy Food and Drink Policy was implemented in Western Australian government schools in 2007. The aim of the present study was to assess the compliance of Western Australian school canteen menus with the policy a decade after its introduction. DESIGN: The traffic-light system that underpins the Healthy Food and Drink Policy categorises foods and drinks into three groups: 'green' healthy items, 'amber' items that should be selected carefully and 'red' items that lack nutritional value. Canteen menus were collected online and each menu item was coded as a green, amber or red choice. SETTING: Western Australia.ParticipantsOnline canteen menus from 136 primary and secondary government schools. RESULTS: The majority of audited school menus met policy requirements to include ≥60 % green items (84 %) and ≤40 % amber items (90 %), but only 52 % completely excluded red items. Overall, approximately half (48 %) of school canteen menus met all three traffic-light targets. On average, 70 % of the menu items were green, 28 % were amber and 2 % were red. Primary-school canteen menus were more likely than those from secondary schools to meet the requirements of the policy. CONCLUSIONS: While the sampled Western Australian government school canteen menus were highly compliant with most of the requirements of the Healthy Food and Drink Policy, many offered red foods and/or drinks. Providing all schools with further education about identifying red items and offering additional services to secondary schools may help improve compliance rates.

Stakeholder perceptions of a school food policy ten years on.

OBJECTIVE: To assess (i) the extent to which stakeholders have accepted and implemented a Healthy Food and Drink Policy for schools a decade after its introduction and (ii) any resulting implications for canteen profitability. DESIGN: Online survey distributed via electronic newsletter to school principals. SETTING: Western Australian public schools. SUBJECTS: Principals, teachers, canteen managers, and parents and citizens committee presidents (n 307). RESULTS: Large majorities of respondents reported that the policy has made the foods and drinks provided in schools healthier (85 %) and that the policy constitutes a good opportunity to teach children about healthy eating (90 %). Only small proportions of respondents felt it had been difficult to implement the policy in their schools (13 %) or that the policy fails to accommodate parents' rights to choose the foods consumed by their children (16 %). Most of the policy outcomes assessed in both the initial post-implementation evaluation (2008) and the 10-year follow-up evaluation (2016) demonstrated significant improvement over time. CONCLUSIONS: The study results indicate that comprehensive school food policies can favourably influence the foods and drinks provided on school premises and can be highly acceptable to key stakeholders, without adversely affecting profitability. The results are encouraging for policy makers in other jurisdictions considering the implementation of similar policies.

Comparison of the nutritional content of the captive and wild diets of the critically endangered mountain chicken frog (Leptodactylus fallax) to improve its captive husbandry.

It is vital to provide appropriate nutrition to maintain healthy populations in conservation breeding programs. Knowledge of the wild diet of a species can be used to inform captive diet formulation. The nutritional content of the wild diet of the critically endangered mountain chicken frog (Leptodactylus fallax) is unknown, like that of most amphibians. In this study, we analyzed the nutritional content of food items that comprise 91% of the wild diet of L. fallax, by dry weight of food items, and all food items offered to captive L. fallax at ZSL London Zoo and Jersey Zoo. We subsequently compared the nutritional content of the wild diet and captive diet at ZSL London Zoo consumed by L. fallax. To the authors' knowledge, this is the first study to directly compare the nutritional content of the wild and captive diets of an anuran amphibian. The captive diet at ZSL London Zoo, without dusting of nutritional supplements, was higher in gross energy and crude fat and lower in ash, calcium and calcium:phosphorus ratio than the wild diet. Most of the food items in the captive diets had a high omega-6:omega-3 fatty acid ratio and in the wild diet had a low omega-6:omega-3 fatty acid ratio. We recommend a combination of modifications to the captive diets to better reflect the nutritional content of the wild diet. Nutritional analysis of captive and wild diets is recommended for other species in conservation breeding programs to improve captive husbandry and ultimately fitness.

ß-adrenergic signaling inhibits Gq-dependent protein kinase D activation by preventing protein kinase D translocation.

RATIONALE: Both ß-adrenergic receptor (ß-AR) and Gq-coupled receptor (GqR) agonist-driven signaling play key roles in the events, leading up to and during cardiac dysfunction. How these stimuli interact at the level of protein kinase D (PKD), a nodal point in cardiac hypertrophic signaling, remains unclear. OBJECTIVE: To assess the spatiotemporal dynamics of PKD activation in response to ß-AR signaling alone and on coactivation with GqR-agonists. This will test our hypothesis that compartmentalized PKD signaling reconciles disparate findings of PKA facilitation and inhibition of PKD activation. METHODS AND RESULTS: We report on the spatial and temporal profiles of PKD activation using green fluorescent protein-tagged PKD (wildtype or mutant S427E) and targeted fluorescence resonance energy transfer-based biosensors (D-kinase activity reporters) in adult cardiomyocytes. We find that ß-AR/PKA signaling drives local nuclear activation of PKD, without preceding sarcolemmal translocation. We also discover pronounced interference of ß-AR/cAMP/PKA signaling on GqR-induced translocation and activation of PKD throughout the cardiomyocyte. We attribute these effects to direct, PKA-dependent phosphorylation of PKD-S427. We also show that phosphomimetic substitution of S427 likewise impedes GqR-induced PKD translocation and activation. In neonatal myocytes, S427E inhibits GqR-evoked cell growth and expression of hypertrophic markers. Finally, we show altered S427 phosphorylation in transverse aortic constriction-induced hypertrophy. CONCLUSIONS: ß-AR signaling triggers local nuclear signaling and inhibits GqR-mediated PKD activation by preventing its intracellular translocation. PKA-dependent phosphorylation of PKD-S427 fine-tunes the PKD responsiveness to GqR-agonists, serving as a key integration point for ß-adrenergic and Gq-coupled stimuli.

Answers at your fingertips: Access to the Internet influences willingness to answer questions.

Recent technological advances have given rise to an information-gathering tool unparalleled by any in human history-the Internet. Understanding how access to such a powerful informational tool influences how we think represents an important question for psychological science. In the present investigation we examined the impact of access to the Internet on the metacognitive processes that govern our decisions about what we "know" and "don't know." Results demonstrated that access to the Internet influenced individuals' willingness to volunteer answers, which led to fewer correct answers overall but greater accuracy when an answer was offered. Critically, access to the Internet also influenced feeling-of-knowing, and this accounted for some (but not all) of the effect on willingness to volunteer answers. These findings demonstrate that access to the Internet can influence metacognitive processes, and contribute novel insights into the operation of the transactive memory system formed by people and the Internet.

Social uncertainty in the digital world.

The social world is inherently uncertain. We present a computational framework for thinking about how increasingly popular online environments modulate the social uncertainty we experience, depending on the type of social inferences we make. This framework draws on Bayesian inference, which involves combining multiple informational sources to update our beliefs.

Affinity and kinetic modulation of polyamide-DNA interactions by N-modification of the heterocycles.

Synthetic N-methyl imidazole and N-pyrrole containing polyamides (PAs) that can form "stacked" dimers can be programmed to target and bind to specific DNA sequences and control gene expression. To accomplish this goal, the development of PAs with lower molecular mass which allows for the molecules to rapidly penetrate cells and localize in the nucleus, along with increased water solubility, while maintaining DNA binding sequence specificity and high binding affinity is key. To meet these challenges, six novel f-ImPy*Im PA derivatives that contain different orthogonally positioned moieties were designed to target 5'-ACGCGT-3'. The synthesis and biophysical characterization of six f-ImPy*Im were determined by CD, ΔTM, DNase I footprinting, SPR, and ITC studies, and were compared with those of their parent compound, f-ImPyIm. The results gave evidence for the minor groove binding and selectivity of PAs 1 and 6 for the cognate sequence 5'-ACGCGT-3', and with strong affinity, Keq = 2.8 × 10(8) M(-1) and Keq = 6.2 × 10(7) M(-1), respectively. The six novel PAs presented in this study demonstrated increased water solubility, while maintaining low molecular mass, sequence specificity, and binding affinity, addressing key issues in therapeutic development.

The performance of transient elastography compared to clinical acumen and routine tests - what is the incremental diagnostic value?

BACKGROUND/AIMS: There is substantial evidence suggesting transient elastography (TE) is a useful tool in assessing liver fibrosis. We aimed to determine whether TE has incremental diagnostic value over clinical acumen and routinely available tests. METHODS: We performed a retrospective study of 130 patients to assess the ability of hepatologists to predict severity of fibrosis using clinical acumen; clinical acumen with routine tests; and elastography in patients with chronic liver disease. The incremental diagnostic benefit was assessed using the area under the ROC curve (AUC) and the Net Reclassification Index (NRI). RESULTS: Using universally available tests, including clinical acumen, the AUCs for detection of cirrhosis ranged from 0.70 to 0.80 for the four hepatologists. Elastography led to statistically non-significant improvements in AUC statistics (range 0.83-0.89; P > 0.01). The detection of significant fibrosis using clinical acumen and routine tests was less accurate, with AUCs of 0.52-0.59. Elastography had incremental diagnostic value (AUC performance range 0.76-0.82; P < 0.01). The NRI indicated that 39-58% were correctly reclassified using elastography, especially with respect to sensitivity. CONCLUSIONS: Our study suggests that the diagnostic value of clinical acumen and routine tests is acceptable for detection of cirrhosis, but not significant fibrosis. Elastography detects significant fibrosis or cirrhosis with acceptable accuracy and offered incremental diagnostic value in detecting significant fibrosis, but not cirrhosis. These findings have implications for determining the diagnostic value of tests over and above routine clinical assessment, which will aid incorporation of novel tests into clinical algorithms.

Fluorescence resonance energy transfer-based sensor Camui provides new insight into mechanisms of calcium/calmodulin-dependent protein kinase II activation in intact cardiomyocytes.

RATIONALE: Calcium/calmodulin-dependent protein kinase II (CaMKII) is a key mediator of intracellular signaling in the heart. However, the tools currently available for assessing dynamic changes in CaMKII localization and activation in living myocytes are limited. OBJECTIVE: We use Camui, a novel FRET-based biosensor in which full-length CaMKII is flanked by CFP and YFP, to measure CaMKII activation state in living rabbit myocytes. METHODS AND RESULTS: We show that Camui and mutant variants that lack the sites of CaMKII autophosphorylation (T286A) and oxidative regulation (CM280/1VV) serve as useful biosensors for CaMKIIδ activation state. Camui (wild-type or mutant) was expressed in isolated adult cardiac myocytes, and localization and CaMKII activation state were determined using confocal microscopy. Camui, like CaMKIIδ, is concentrated at the z-lines, with low baseline activation state. Camui activation increased directly with pacing frequency, but the maximal effect was blunted with the T286A, consistent with frequency-dependent phosphorylation of CaMKII at T286 mainly at high-frequency and high-amplitude Ca transients. Camui was also activated by 4 neurohormonal agonists. Angiotensin II and endothelin-1 activated Camui, largely through an oxidation-dependent mechanism, whereas isoproterenol- and phenylephrine-mediated mechanisms had a significant autophosphorylation-dependent component. CONCLUSIONS: Camui is a novel, nondestructive tool that allows spatiotemporally resolved measurement of CaMKII activation state in physiologically functioning myocytes. This represents a first step in using Camui to elucidate key mechanistic details of CaMKII signaling in live hearts and myocytes.

Design, synthesis, and DNA binding characteristics of a group of orthogonally positioned diamino, N-formamido, pyrrole- and imidazole-containing polyamides.

Orthogonally positioned diamino/dicationic polyamides (PAs) have good water solubility and enhanced binding affinity, whilst retaining DNA minor groove and sequence specificity compared to their monoamino/monocationic counterparts. The synthesis and DNA binding properties of the following diamino PAs: f-IPI (3a), f-IPP (4), f-PIP (5), and f-PPP (6) are described. P denotes the site where a 1-propylamino group is attached to the N1-position of the heterocycle. Binding of the diamino PAs to DNA was assessed by DNase I footprinting, thermal denaturation, circular dichroism titration, biosensor surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC) studies. According to SPR studies, f-IPI (3a) bound more strongly (K(eq)=2.4×10(8) M(-1)) and with comparable sequence selectivity to its cognate sequence 5'-ACGCGT-3' when compared to its monoamino analog f-IPI (1). The binding of f-IPI (3a) to 5'-ACGCGT-3' via the stacked dimer motif was balanced between enthalpy and entropy, and that was quite different from the enthalpy-driven binding of its monoamino parent f-IPI (1). f-IPP (4) also bound more strongly to its cognate sequence 5'-ATGCAT-3' (K(eq)=7.4×10(6) M(-1)) via the side-by-side stacked motif than its monoamino analog f-IPP (2a). Although f-PPP (6) bound via a 1:1 motif, it bound strongly to its cognate sequence 5'-AAATTT-3' (K(eq)=4.8×10(7) M(-1)), 15-times higher than the binding of its monoamino analog f-PPP (2c), albeit f-PPP bound via the stacked motif. Finally, f-PIP (5) bound to its target sequence 5'-ATCGAT-3' as a stacked dimer and it has the lowest affinity among the diamino PAs tested (Keq <1×10(5) M(-1)). This was about two times lower in affinity than the binding of its monoamino analog f-PIP (2b). The results further demonstrated that the 'core rules' of DNA recognition by monoamino PAs also apply to their diamino analogs. Specifically, PAs that contain a stacked IP core structure bind most strongly (highest binding constants) to their cognate GC doublet, followed by the binding of PAs with a stacked PP structure to two degenerate AT base pairs, and finally the binding of PAs with a PI core to their cognate CG doublet.

Do humans prefer cognitive effort over doing nothing?

Humans and other animals find mental (and physical) effort aversive and have the fundamental drive to avoid it. However, doing nothing is also aversive. Here, we ask whether people choose to avoid effort when the alternative is to do nothing at all. Across 12 studies, participants completed variants of the demand selection task, in which they repeatedly selected between a cognitively effortful task (e.g., simple addition, Stroop task, and symbol-counting task) and a task that required no effort (e.g., doing nothing, watching the computer complete the Stroop, and symbol-viewing). We then tabulated people's choices. Across our studies and an internal meta-analysis, we found little evidence that people choose to avoid effort (and hints that people sometimes prefer effort) when the alternative was doing nothing. Our findings suggest that doing nothing can be just as costly-if not more costly-than exerting effort. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Hx, a novel fluorescent, minor groove and sequence specific recognition element: design, synthesis, and DNA binding properties of p-anisylbenzimidazole-imidazole/pyrrole-containing polyamides.

With the aim of incorporating a recognition element that acts as a fluorescent probe upon binding to DNA, three novel pyrrole (P) and imidazole (I)-containing polyamides were synthesized. The compounds contain a p-anisylbenzimidazolecarboxamido (Hx) moiety attached to a PP, IP, or PI unit, giving compounds HxPP (2), HxIP (3), and HxPI (4), respectively. These fluorescent hybrids were tested against their complementary nonfluorescent, non-formamido tetraamide counterparts, namely, PPPP (5), PPIP (6), and PPPI (7) (cognate sequences 5'-AAATTT-3', 5'-ATCGAT-3', and 5'-ACATGT-3', respectively). The binding affinities for both series of polyamides for their cognate and noncognate sequences were ascertained by surface plasmon resonance (SPR) studies, which revealed that the Hx-containing polyamides gave binding constants in the 10(6) M(-1) range while little binding was observed for the noncognates. The binding data were further compared to the corresponding and previously reported formamido-triamides f-PPP (8), f-PIP (9), and f-PPI (10). DNase I footprinting studies provided additional evidence that the Hx moiety behaved similarly to two consecutive pyrroles (PP found in 5-7), which also behaved like a formamido-pyrrole (f-P) unit found in distamycin and many formamido-triamides, including 8-10. The biophysical characterization of polyamides 2-7 on their binding to the abovementioned DNA sequences was determined using thermal melts (ΔT(M)), circular dichroism (CD), and isothermal titration calorimetry (ITC) studies. Density functional calculations (B3LYP) provided a theoretical framework that explains the similarity between PP and Hx on the basis of molecular electrostatic surfaces and dipole moments. Furthermore, emission studies on polyamides 2 and 3 showed that upon excitation at 322 nm binding to their respective cognate sequences resulted in an increase in fluorescence at 370 nm. These low molecular weight polyamides show promise for use as probes for monitoring DNA recognition processes in cells.

Design, synthesis and DNA binding properties of orthogonally positioned diamino containing polyamide f-IPI.

An orthogonally positioned diamino/dicationic polyamide f-IPI 2 was synthesized. It has enhanced binding affinity, and it showed comparable sequence specificity to its monoamino/monocationic counterpart f-IPI 1. Results from CD and DNase I footprinting studies confirmed the minor groove binding and selectivity of polyamides 1 and 2 for the cognate sequence 5'-ACGCGT-3'. SPR studies provided their binding constants: 2.4 × 10(8)M(-1) for diamino 2, which is ∼4 times higher than 5.4 × 10(7)M(-1) for its monoamino analogue 1.

Evidence for diversity in the activation of the melanocortin 2 receptor: A study on gar, elephant shark and stingray MC2Rs.

The melanocortin-2 receptor (MC2R) is a critical component of the HPI and HPA axes of cartilaginous fishes, teleosts and tetrapods. Studies on teleost and tetrapod orthologs suggest two contact sites between ACTH and the receptor involving the following motifs on ACTH: H6F7R8W9 and K15K16R17R18P19. Using spotted gar (g) MC2R as a representative bony fish MC2R ortholog, we found that activation of gMC2R in Chinese Hamster Ovary (CHO) cells was diminished following stimulation of the transfected cells with hACTH(1-24) analogs substituted with alanine at either the H6F7R8W9 or K15K16R17R18P19 motifs compared to stimulation with hACTH(1-24). This observation suggests two ligand contact sites necessary for activation of the gMC2R. The same experiments were done with elephant shark (es) MC2R, however only the H6F7R8W9 analogs blocked activation, pointing to a single contact on esMC2R. Conversely, the red stingray (sr) MC2R activation was blocked by both the H6F7R8W9 and K15K16R17R18P19 alanine-substituted analogs. Together these results build a picture of the evolution of the ligand and receptor interaction between ACTH and MC2R orthologs of different taxa. These results will be discussed in light of the parallel evolution of MC2R orthologs in cartilaginous fishes and bony vertebrates.