B Cells and T Follicular Helper Cells Mediate Response to Checkpoint Inhibitors in High Mutation Burden Mouse Models of Breast Cancer.

This study identifies mechanisms mediating responses to immune checkpoint inhibitors using mouse models of triple-negative breast cancer. By creating new mammary tumor models, we find that tumor mutation burden and specific immune cells are associated with response. Further, we developed a rich resource of single-cell RNA-seq and bulk mRNA-seq data of immunotherapy-treated and non-treated tumors from sensitive and resistant murine models. Using this, we uncover that immune checkpoint therapy induces T follicular helper cell activation of B cells to facilitate the anti-tumor response in these models. We also show that B cell activation of T cells and the generation of antibody are key to immunotherapy response and propose a new biomarker for immune checkpoint therapy. In total, this work presents resources of new preclinical models of breast cancer with large mRNA-seq and single-cell RNA-seq datasets annotated for sensitivity to therapy and uncovers new components of response to immune checkpoint inhibitors.

Anti-PD-1 Checkpoint Therapy Can Promote the Function and Survival of Regulatory T Cells.

We have previously shown in a model of claudin-low breast cancer that regulatory T cells (Tregs) are increased in the tumor microenvironment (TME) and express high levels of PD-1. In mouse models and patients with triple-negative breast cancer, it is postulated that one cause for the lack of activity of anti-PD-1 therapy is the activation of PD-1-expressing Tregs in the TME. We hypothesized that the expression of PD-1 on Tregs would lead to enhanced suppressive function of Tregs and worsen antitumor immunity during PD-1 blockade. To evaluate this, we isolated Tregs from claudin-low tumors and functionally evaluated them ex vivo. We compared transcriptional profiles of Tregs isolated from tumor-bearing mice with or without anti-PD-1 therapy using RNA sequencing. We found several genes associated with survival and proliferation pathways; for example, Jun, Fos, and Bcl2 were significantly upregulated in Tregs exposed to anti-PD-1 treatment. Based on these data, we hypothesized that anti-PD-1 treatment on Tregs results in a prosurvival phenotype. Indeed, Tregs exposed to PD-1 blockade had significantly higher levels of Bcl-2 expression, and this led to increased protection from glucocorticoid-induced apoptosis. In addition, we found in vitro and in vivo that Tregs in the presence of anti-PD-1 proliferated more than control Tregs PD-1 blockade significantly increased the suppressive activity of Tregs at biologically relevant Treg/Tnaive cell ratios. Altogether, we show that this immunotherapy blockade increases proliferation, protection from apoptosis, and suppressive capabilities of Tregs, thus leading to enhanced immunosuppression in the TME.

Vitamin D receptor and metabolite effects on corneal epithelial cell gap junction proteins.

Vitamin D is a fat-soluble prohormone that can be activated both systemically and within individual tissues. Our lab has previously demonstrated that the corneal epithelium can activate vitamin D and that the vitamin D metabolites 1,25(OH)2D3 and 24R,25(OH)2D3 can affect corneal epithelial migration, proliferation, and tight and gap junction function. These vitamin D-derived metabolites signal through the vitamin D receptor (VDR). The purpose of this study was to specifically determine the effects of 1,25(OH)2D3 and 24R,25(OH)2D3 on corneal epithelial cell gap junction proteins. Connexin (Cx) 26, 30 and 43 protein expression was detected in a human corneal epithelial cell line (HCEC), wild type and vitamin D receptor knockout (VDR-/-) mouse corneas, and cultured mouse primary epithelial cells (MPCEC). In vitro gap junction function was assessed using the scrape loading/dye transfer assay. HCEC and MPCEC were treated with 1,25(OH)2D3 or 24R,25(OH)2D3. Western blotting was used to detect gap junction proteins. Vitamin D3 effects on epithelial intracellular Ca++ (Ca++i) were determined using the dye Cal-520. Cx26 and Cx43 protein levels were significantly increased in HCEC and MPCEC treated with both 1,25(OH)2D3 and 24R,25(OH)2D3. Cx30 and Cx43 protein levels were also significantly increased in VDR-/- MPCEC. In vitro gap junction connectivity was significanlty enhanced in HCEC and MPCEC cultured with 24R,25(OH)2D3 and 1,25(OH)2D3. Ca++i was not affected by 1,25(OH)2D3 or 24R,25(OH)2D3 in HCEC or MPCEC. We conclude that both 1,25(OH)2D3 and 24R,25(OH)2D3 are positive regulators of connexin proteins and gap junction communication in the corneal epithelium. These vitamin D metabolites appear to signal through both VDR-dependent and -independent pathways. The effects of vitamin D on corneal epithelial gap junctions do not seem to be dependent on Ca++i.

IRF-3, IRF-5, and IRF-7 coordinately regulate the type I IFN response in myeloid dendritic cells downstream of MAVS signaling.

Although the transcription factors IRF-3 and IRF-7 are considered master regulators of type I interferon (IFN) induction and IFN stimulated gene (ISG) expression, Irf3(-/-)×Irf7(-/-) double knockout (DKO) myeloid dendritic cells (mDC) produce relatively normal levels of IFN-ß after viral infection. We generated Irf3(-/-)×Irf5(-/-)×Irf7(-/-) triple knockout (TKO) mice to test whether IRF-5 was the source of the residual induction of IFN-ß and ISGs in mDCs. In pathogenesis studies with two unrelated positive-sense RNA viruses (West Nile virus (WNV) and murine norovirus), TKO mice succumbed at rates greater than DKO mice and equal to or approaching those of mice lacking the type I IFN receptor (Ifnar(-/-)). In ex vivo studies, after WNV infection or exposure to Toll-like receptor agonists, TKO mDCs failed to produce IFN-ß or express ISGs. In contrast, this response was sustained in TKO macrophages following WNV infection. To define IRF-regulated gene signatures, we performed microarray analysis on WNV-infected mDC from wild type (WT), DKO, TKO, or Ifnar(-/-) mice, as well as from mice lacking the RIG-I like receptor adaptor protein MAVS. Whereas the gene induction pattern in DKO mDC was similar to WT cells, remarkably, almost no ISG induction was detected in TKO or Mavs(-/-) mDC. The relative equivalence of TKO and Mavs(-/-) responses suggested that MAVS dominantly regulates ISG induction in mDC. Moreover, we showed that MAVS-dependent induction of ISGs can occur through an IRF-5-dependent yet IRF-3 and IRF-7-independent pathway. Our results establish IRF-3, -5, and -7 as the key transcription factors responsible for mediating the type I IFN and ISG response in mDC during WNV infection and suggest a novel signaling link between MAVS and IRF-5.

Perception of available space during chimpanzee introductions: Number of accessible areas is more important than enclosure size.

Restricting animals to different areas of their enclosure, for both brief and extended durations, is a key element of animal management practices. With such restrictions, available space decreases and the choices the animals can make are more limited, particularly in relation to social dynamics. When unfamiliar individuals are introduced to each other, group dynamics can be unpredictable and understanding space usage is important to facilitate successful introductions. We studied the behavioral, welfare-related responses of two groups of zoo-housed chimpanzees (n = 22) as they were introduced to each other and experienced a variety of enclosure restrictions and group composition changes. Our analysis of available space while controlling for chimpanzee density, found that arousal-related scratching and yawning decreased as the number of enclosure areas (separate rooms) available increased, whereas only yawning decreased as the amount of available space (m(2)) increased. Allogrooming, rubbing, and regurgitation/reingestion rates remained constant as both the number of enclosure areas and amount of space changed. Enclosure space is important to zoo-housed chimpanzees, but during introductions, a decrease in arousal-related scratching indicates that the number of accessible areas is more important than the total amount of space available, suggesting that it is important to provide modular enclosures that provide choice and flexible usage, to minimize the welfare impact of short- and long-term husbandry needs.

Pattern recognition receptor MDA5 modulates CD8+ T cell-dependent clearance of West Nile virus from the central nervous system.

Many viruses induce type I interferon responses by activating cytoplasmic RNA sensors, including the RIG-I-like receptors (RLRs). Although two members of the RLR family, RIG-I and MDA5, have been implicated in host control of virus infection, the relative role of each RLR in restricting pathogenesis in vivo remains unclear. Recent studies have demonstrated that MAVS, the adaptor central to RLR signaling, is required to trigger innate immune defenses and program adaptive immune responses, which together restrict West Nile virus (WNV) infection in vivo. In this study, we examined the specific contribution of MDA5 in controlling WNV in animals. MDA5(-/-) mice exhibited enhanced susceptibility, as characterized by reduced survival and elevated viral burden in the central nervous system (CNS) at late times after infection, even though small effects on systemic type I interferon response or viral replication were observed in peripheral tissues. Intracranial inoculation studies and infection experiments with primary neurons ex vivo revealed that an absence of MDA5 did not impact viral infection in neurons directly. Rather, subtle defects were observed in CNS-specific CD8(+) T cells in MDA5(-/-) mice. Adoptive transfer into recipient MDA5(+/+) mice established that a non-cell-autonomous deficiency of MDA5 was associated with functional defects in CD8(+) T cells, which resulted in a failure to clear WNV efficiently from CNS tissues. Our studies suggest that MDA5 in the immune priming environment shapes optimal CD8(+) T cell activation and subsequent clearance of WNV from the CNS.

The repertoire and intentionality of gestural communication in wild chimpanzees.

A growing body of evidence suggests that human language may have emerged primarily in the gestural rather than vocal domain, and that studying gestural communication in great apes is crucial to understanding language evolution. Although manual and bodily gestures are considered distinct at a neural level, there has been very limited consideration of potential differences at a behavioural level. In this study, we conducted naturalistic observations of adult wild East African chimpanzees (Pan troglodytes schweinfurthii) in order to establish a repertoire of gestures, and examine intentionality of gesture production, use and comprehension, comparing across manual and bodily gestures. At the population level, 120 distinct gesture types were identified, consisting of 65 manual gestures and 55 bodily gestures. Both bodily and manual gestures were used intentionally and effectively to attain specific goals, by signallers who were sensitive to recipient attention. However, manual gestures differed from bodily gestures in terms of communicative persistence, indicating a qualitatively different form of behavioural flexibility in achieving goals. Both repertoire size and frequency of manual gesturing were more affiliative than bodily gestures, while bodily gestures were more antagonistic. These results indicate that manual gestures may have played a significant role in the emergence of increased flexibility in great ape communication and social bonding.

Participation in a Prison-Based Training Programme Is Beneficial for Rescue Dogs.

Dogs are often relinquished because of behavioural issues which may be exacerbated in rehoming centres. Prison-based dog training programmes (DTPs) may enhance outcomes for rescue dogs by providing socialisation and training opportunities to improve behaviour, welfare and likelihood of rehoming. We assessed whether dogs benefitted from participation, 1-3 times per week, in a prison-based DTP in which male young offenders learn how to train and care for dogs waiting to be rehomed. Within DTP sessions, there was significant improvement on a range of training tasks (n = 42 dogs). Analyses of videos (n = 17 dogs) in the kennels and a training barn pre- and post-DTP participation showed improvement in some positive behaviours, but no significant change in other behaviours. Subjective ratings by staff of the dogs' behaviour were made (n = 20 dogs). Desirable behaviours (e.g., playful/friendly) increased, and most undesirable behaviours (e.g., frustrated and noisy) decreased. Participation in the DTP did not mitigate all negative behaviours. However, improvements are consistent with enhanced welfare and likelihood of successful rehoming. Prison-based DTPs can be effective in supporting the work of animal rescue organisations to improve outcomes for dogs, while offering people in custody an opportunity to engage in purposeful activity and provide a community service.

Bacterial vaginosis-driven changes in vaginal T cell phenotypes and their implications for HIV susceptibility.

Bacterial vaginosis (BV) is a dysbiosis of the vaginal microbiome that is prevalent in reproductive-age women worldwide. Adverse outcomes associated with BV include an increased risk of sexually acquired Human Immunodeficiency Virus (HIV), yet the immunological mechanisms underlying this association are not well understood. To investigate BV driven changes to cervicovaginal tract (CVT) and circulating T cell phenotypes, participants with or without BV provided vaginal tract (VT) and ectocervical (CX) tissue biopsies and peripheral blood mononuclear cells (PBMC). Immunofluorescence analysis of genital mucosal tissues revealed a reduced density of CD3+CD4+CCR5+ cells in the VT lamina propria of individuals with compared to those without BV (median 243.8 cells/mm2 BV- vs 106.9 cells/mm2 BV+, p=0.043). High-parameter flow cytometry of VT biopsies revealed an increased frequency in individuals with compared to those without BV of dysfunctional CD39+ conventional CD4+ T cells (Tconv) (median frequency 15% BV- vs 30% BV+, padj=0.0331) and tissue-resident CD69+CD103+ Tconv (median frequency 24% BV- vs 38% BV+, padj=0.0061), previously reported to be implicated in HIV acquisition and replication. Our data suggests that BV elicits diverse and complex VT T cell alterations and expands on potential immunological mechanisms that may promote adverse outcomes including HIV susceptibility.

Communicative intentions in wild chimpanzees: persistence and elaboration in gestural signalling.

We examine evidence for communicative intent during conspecific interactions in wild chimpanzees (Budongo Forest, Uganda), focusing on persistence in gestural communication. Previous research indicates that great apes have large gestural repertoires and produce gestural communication in a flexible and intentional manner, including the production of gesture sequences. Although there is a lack of consensus on the form and function of sequences, there is some evidence that sequences are produced when signallers fail to receive any response from a recipient. Here, we provide first systematic evidence for communicative persistence in wild chimpanzees. Rather than examining only the presence or absence of a response, we used the most commonly observed response to assign meanings to gestures and examined sequence production in relation to response congruency. Chimpanzees ceased communication if successful, but persevered when unsuccessful. Chimpanzees repeated gestures when a response partially matched their goal but substituted the original gesture when a response was incongruent. Persistence was also mediated by recipient intent to respond, with more sequences produced within competitive than affiliative contexts. Gestures within sequences were homogenous in semantic meaning and signallers continued until the response matched the assigned meaning of the initial gesture. Gestural sequence production was not primarily affective; gesture intensity (in terms of modality) did not increase within sequences. Chimpanzee gestural sequences emerged to achieve specific outcomes; given variability in recipient behaviour following initial gestures, signallers were flexible in their persistence towards these goals.

Preparing Interns as Teachers: Teaching Fourth-Year Medical Students the Tenets of the One-Minute Preceptor Model.

Introduction: Often, interns are expected to teach medical students early in their residency, but most are not formally taught how to be effective teachers before residency. Currently, there is emphasis on developing teaching skills of residents rather than students before they become residents. Most published student-as-teacher courses are voluntary and do not assess skill acquisition. Methods: We taught 290 fourth-year medical students across two academic years (2020-2022) the tenets of the One-Minute Preceptor (OMP) using a 2-hour workshop during their transition to residency course. A variety of role-play cases allowed students to practice the different parts of the OMP in isolation and combined. Then, we assessed their teaching skills after the workshop using an objective structured teaching exam (OSTE). Results: Two hundred seventy-eight students (96%) completed the self-assessment of their confidence demonstrating the skills of the OMP before and after the workshop. Their confidence improved in all domains, with ps < .001. Additionally, all students successfully demonstrated competency on the OSTE. Discussion: We used a 2-hour workshop based on the OMP to improve fourth-year medical students' confidence in their teaching skills and allow them to demonstrate competence in those skills before starting their intern year.

Waiting for more: the performance of domestic dogs (Canis familiaris) on exchange tasks.

Five domestic dogs (Canis familiaris) were tested in a cooperative exchange task with an experimenter, as previously tested in non-human primates. In the first task, the dogs exchanged to maximise payoffs when presented with food items of differing quality. All consistently exchanged lower-value for higher-value rewards, as determined by their individual food preference, and exchanges corresponded significantly with the spontaneous preferences of three dogs. Next, all subjects demonstrated an ability to perform two and three exchanges in succession, to gain both qualitative and quantitatively increased rewards (group mean = 72 and 92% successful triple exchanges, respectively). Finally, the ability to delay gratification over increasing intervals was tested; the dogs kept one food item to exchange later for a larger item. As previously reported in non-human primates, there was considerable individual variation in the tolerance of delays, between 10 s and 10 min for the largest rewards. For those who reached longer time lags (>40 s), the dogs gave up the chance to exchange earlier than expected by each subject's general waiting capacity; the dogs anticipated delay duration and made decisions according to the relative reward values offered. Compared to primates, dogs tolerated relatively long delays for smaller value rewards, suggesting that the socio-ecological history of domestic dogs facilitates their performance on decision-making and delay of gratification tasks.

Cognitive research in zoo-housed chimpanzees: influence of personality and impact on welfare.

We monitored chimpanzee welfare during the introduction of on-exhibit cognitive research training and testing, as measured by behavior and interest in such training, and related individual variation to personality assessments. We observed 11 chimpanzees (six males; five females) over a 16-month period and compared their behavior across three conditions: (1) Baseline (nontraining/research situations) and (2) an on-going, off-exhibit program of Husbandry Training and (3) Research Pod Activities, on-exhibit, group training for cognitive testing. There was considerable individual variation in their interest levels during research sessions; females and those scoring higher for Openness were present more frequently (including those who actively participated and those who observed others participating), but interest did not vary in relation to rates of self-directed behaviors (SDBs), rank, or the level of social disruptions within the group (i.e. large-scale displays or fights). The frequency of SDBs was predicted by the Neuroticism personality factor, but did not differ across baseline and training contexts, indicating that these activities do not negatively impact welfare. We also explored vigilance as an indicator of social uncertainty, but social monitoring did not differ in relation to either social context or rank. Finally, we explored how the specific characteristics of the research context impacted on SDBs; namely, social context, reward contingency, and visual access to keepers. SDBs increased only when visual access to keepers was restricted, suggesting that visual contact reduced uncertainty in novel training contexts. Overall, the introduction of a cognitive research program did not compromise welfare, and the chimpanzees' repeated interest and willingness to participate suggests that the research was enriching.

Practice Doesn't Make Perfect: Clinical Experience With Procedures Does Not Correlate Well With Competence in Third-Year Medical Students.

OBJECTIVE: There is limited data available about factors which promote competence with procedures in medical students. Specifically, the relationship between procedural clinical experience and performance on an assessment is unclear. We sought to determine whether a correlation exists between the amount and type of clinical experience with a procedure and student performance on a standardized assessment of that procedure. DESIGN: Faculty performed standardized assessments of third-year medical students on ten procedures using simulation. We prospectively surveyed students about 3 types of experience (performed, observed, and simulated) with these procedures during their clerkships. We then analyzed whether a correlation exists between student experience and their competency assessment scores using Pearson's correlation. SETTING/PARTICIPANTS: Third-year medical students at the University of Kentucky College of Medicine. RESULTS: In 2018 to 2019, 131 students were assessed on procedural competency with 10 failures. One hundred and twenty students (91.6%) completed the clinical experience survey. Correlations between types of experience and competency scores were small to moderate, with only 5 of 40 being significant. We found no correlation between experience having performed a procedure and competency score. CONCLUSIONS: Overall, we did not find convincing evidence of a correlation between experience with procedures during clerkships and performance on a competency assessment. This suggests other factors may be contributing to procedural competence, which has implications for how educators should develop procedural competence in students.

Mucosal viral infection induces a regulatory T cell activation phenotype distinct from tissue residency in mouse and human tissues.

Regulatory T cells (Tregs) mediate immune homeostasis, yet also facilitate nuanced immune responses during infection, balancing pathogen control while limiting host inflammation. Recent studies have identified Treg populations in non-lymphoid tissues that are phenotypically distinct from Tregs in lymphoid tissues (LT), including performance of location-dependent roles. Mucosal tissues serve as critical barriers to microbes while performing unique physiologic functions, so we sought to identify distinct phenotypical and functional aspects of mucosal Tregs in the female reproductive tract. In healthy human and mouse vaginal mucosa, we found that Tregs are highly activated compared to blood or LT Tregs. To determine if this phenotype reflects acute activation or a general signature of vaginal tract (VT)-residency, we infected mice with HSV-2 to discover that VT Tregs express granzyme-B (GzmB) and acquire a VT Treg signature distinct from baseline. To determine the mechanisms that drive GzmB expression, we performed ex vivo assays to reveal that a combination of type-I interferons and interleukin-2 is sufficient for GzmB expression. Together, we highlight that VT Tregs are activated at steady state and become further activated in response to infection; thus, they may exert robust control of local immune responses, which could have implications for mucosal vaccine design.

The human memory T cell compartment changes across tissues of the female reproductive tract.

Memory CD4 T cells in tissues fulfill numerous functions that are critical for local immune homeostasis and protection against pathogens. Previous studies have highlighted the phenotypic and functional heterogeneity of circulating and tissue-resident memory CD4 T cells across different human tissues such as skin, lung, liver, and colon. Comparatively little is known in regard to memory CD4 T cells across tissues of the female reproductive tract (FRT). We examined CD4 T cells in donor-matched vaginal, ecto- and endocervical tissues, which differ in mucosal structure and exposure to external environmental stimuli. We hypothesized that this could be reflected by tissue-specific differences in the memory CD4 T cell compartment. We found differences in CD4 subset distribution across these tissues. Specifically, CD69+CD103+ CD4 T cells were significantly more abundant in vaginal than cervical tissues. In contrast, the transcriptional profiles of CD4 subsets were fairly conserved across FRT tissues. CD69+CD103+ CD4 T cells showed a TH17 bias independent of tissue niche. Our data suggest that FRT tissues affect T cell subset distribution but have limited effects on the transcriptome of each subset. We discuss the implications for barrier immunity in the FRT.

A differential regulatory T cell signature distinguishes the immune landscape of COVID-19 hospitalized patients from those hospitalized with other respiratory viral infections.

SARS-CoV-2 infection has caused a lasting global pandemic costing millions of lives and untold additional costs. Understanding the immune response to SARS-CoV-2 has been one of the main challenges in the past year in order to decipher mechanisms of host responses and interpret disease pathogenesis. Comparatively little is known in regard to how the immune response against SARS-CoV-2 differs from other respiratory infections. In our study, we compare the peripheral blood immune signature from SARS-CoV-2 infected patients to patients hospitalized pre-pandemic with Influenza Virus or Respiratory Syncytial Virus (RSV). Our in-depth profiling indicates that the immune landscape in patients infected by SARS-CoV-2 is largely similar to patients hospitalized with Flu or RSV. Similarly, serum cytokine and chemokine expression patterns were largely overlapping. Unique to patients infected with SARS-CoV-2 who had the most critical clinical disease state were changes in the regulatory T cell (Treg) compartment. A Treg signature including increased frequency, activation status, and migration markers was correlated with the severity of COVID-19 disease. These findings are particularly relevant as Tregs are being discussed as a therapy to combat the severe inflammation seen in COVID-19 patients. Likewise, having defined the overlapping immune landscapes in SARS-CoV-2, existing knowledge of Flu and RSV infections could be leveraged to identify common treatment strategies. HIGHLIGHTS: The immune landscapes of hospitalized pre-pandemic RSV and influenza patients are similar to SARS-CoV-2 patientsSerum cytokine and chemokine expression patterns are largely similar between patients hospitalized with respiratory virus infections, including SARS-CoV-2, versus healthy donorsSARS-CoV-2 patients with the most critical disease displayed unique changes in the Treg compartmentadvances in understanding and treating SARS-CoV-2 could be leveraged for other common respiratory infections.

A regulatory T cell signature distinguishes the immune landscape of COVID-19 patients from those with other respiratory infections.

Despite recent studies of immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), little is known about how the immune response against SARS-CoV-2 differs from other respiratory infections. We compare the immune signature from hospitalized SARS-CoV-2­infected patients to patients hospitalized prepandemic with influenza or respiratory syncytial virus (RSV). Our in-depth profiling indicates that the immune landscape in SARS-CoV-2 patients is largely similar to flu or RSV patients. Unique to patients infected with SARS-CoV-2 who had the most critical clinical disease were changes in the regulatory T cell (Treg) compartment. A Treg signature including increased frequency, activation status, and migration markers was correlated COVID-19 severity. These findings are relevant as Tregs are considered for therapy to combat the severe inflammation seen in COVID-19 patients. Likewise, having defined the overlapping immune landscapes in SARS-CoV-2, existing knowledge of flu and RSV infections could be leveraged to identify common treatment strategies.

How do African grey parrots (Psittacus erithacus) perform on a delay of gratification task?

Humans and other animals often find it difficult to choose a delayed reward over an immediate one, even when the delay leads to increased pay-offs. Using a visible incremental reward procedure, we tested the ability of three grey parrots to maintain delay of gratification for an increasingly valuable food pay-off. Up to five sunflower seeds were placed within the parrot's reach, one at a time, at a rate of one seed per second. When the parrot took a seed the trial was ended and the birds consumed the accumulated seeds. Parrots were first tested in daily sessions of ten trials and then with single daily trials. For multiple trial sessions, all three parrots showed some limited improvement across 30 sessions. For single trial sessions, only one parrot showed any increase in seed acquisition across trials. This parrot was also able to consistently obtain two or more seeds per trial (across both multiple and single trial conditions) but was unable to able to wait 5 s to obtain the maximum number of seeds. This parrot was also tested on a slower rate of seed presentation, and this significantly reduced her mean seed acquisition in both multiple and single trial conditions, suggesting that both value of reward available and delay duration impact upon self-control. Further manipulation of both the visibility and proximity of seeds during delay maintenance had little impact upon tolerance of delays for both parrots tested in this condition. This task demanded not just a choice of delayed reward but the maintenance of delayed gratification and was clearly difficult for the parrots to learn; additional training or alternative paradigms are required to better understand the capacity for self-control in this and other species.

Variation and context of yawns in captive chimpanzees (Pan troglodytes).

Primate yawns are usually categorized according to context (e.g. as a threat, anxious, or rest yawn), but there has been little consideration of whether these yawns are best regarded as a unitary behavior that only differs with respect to the context in which it is observed. This study examined the context and precise morphology of yawns in a group of 11 captive chimpanzees. Focal video sampling was used to describe the morphology and intensity of 124 yawns using ChimpFACS, a system for coding facial movements. Two distinct forms of yawn were identified, a full yawn and a yawn which is modified by additional actions that reduce the mouth aperture. These modified yawns may indicate some degree of voluntary control over facial movement in chimpanzees and, consequently, multiple functions of yawning according to context. To assess context effects, mean activity levels (resting, locomotion, and grooming) and scratching rates were compared one minute before and after each yawn. Locomotion was significantly increased following both types of yawn, whereas scratching rates significantly increased following modified yawns but decreased following full yawns. In terms of individual differences, males did not yawn more than females, although male yawns were of higher intensity, both in the degree of mouth opening and in the amount of associated head movement. These data indicate that yawning is associated with a change in activity levels in chimpanzees, but only modified yawns may be related to increased arousal. Different types of yawn can therefore be differentiated at the morphological level as well as context level.