Factors influencing the olfactory capabilities of foraging rodents

Granivorous rodents living within rich communities of scatter-hoarding speciespartially rely on olfaction as a foraging strategy to locate buried seeds.While abiotic factors are well known to influence the olfactory capabilities of foraging rodents, we know less about how seed olfactory cues may change over time, how attributes of seed resources themselves affect olfactory cues, or exactly what type of odors are being detected. Such questions are worth investigating, as olfactory cues may influence resource partitioning in arid ecosystems through their importance to a rodent's foraging strategy. I investigate three hypotheses in the first chapter, 1) the olfactory signal of seeds buried in dry soil diminishes over time, 2) the presence of a seed's hardened seed coat acts to diminish olfactory cues, and 3) the olfactory signal of buried seeds increases following rain events. Data collected using artificial foraging grids in Little Valley, NV, and laboratory foraging trials, suggest that a seed's soil residence time does not alone significantly affect rodents' ability to detect cached seeds, and in fact, localized disturbances associated with seed burial may slightly increase cache detection.Alternatively, a seed's hardened, durable shell does appear to play an important role in reducing detection by naïve foragers. Further, my experimental evidence showed that rodents were more likely to retrieve their own caches, than pilfer, in moist soil conditions. In chapter two I investigated the hypotheses that 1) Jeffrey pine seeds contain volatile terpenoids (VTs) that contribute to seed odor, 2) VTs are used as cues when rodents forage for buried seeds, and 3) rodents can detect individual macronutrients. I used similar investigative techniques as those in chapter 1, with the addition of solidphase micro-extraction (SPME) paired with gas chromatography/mass spectrometry (GC/MS) headspace analysis. Jeffrey pine seeds were found to contain 16 compounds, most of which were released from whole, wetted seeds. The majority of compounds appeared to emanate from the seed coat rather than the nutrient-containing seed embryo. One of these, (-)ß-pinene, was found to illicit digging behavior in the lab, while another, (-)R-Limonene, had no such effect. When isolated macronutrients were presented to chipmunks, lipids and proteins were found most successfully, while carbohydrates were not. Cumulatively these data suggest that the chemosensory information available within seed resource may be as important in making foraging decisions as they are in social and predator awareness contexts. As effective density dependent predators, rodents pressure plant resources to balance selective costs of dispersal with loss to seed predators, pathogens, and fungi. The high preference of rodents for Jeffrey pine seeds and the presence of a variety of terpenoid compounds within them suggest that these balancing mechanisms have already been at work shaping plant-animal interactions in an animal-dispersed pine

MT Legislature and Wildlife 101

Bob Ream and Jake Troyer will lead an educational discussion about the Montana Legislature.  The discussion will center on the best ways to engage with legislators, critical wildlife legislation introduced in the 2015 Montana Legislature, and how you can get involved as a citizen advocate on the issues that are most important to you

The impact of the manufacturing process on the surface quality of polyethylene terephthalate optical film

This study aims to understand the ways in which the conditions of the manufacturing process of polyethylene terephthalate film can affect the surface quality of clear optical films. The purpose of gaining this understanding was to improve on existing cleaning methods and processing conditions that are currently insufficient and lead to a decrease in surface quality over time. Flexible electronics is a growing industry within the technology sector. This growth drives demand for screens which are both flexible and scratch resistant. DuPont Teijin Films (DTF) focuses on rapid innovative product development and aspires to produce high quality, optically clear film for flexible electronic applications. An obstacle to development is the requirement for impeccable surface quality. Through this work it has been confirmed that the presence of contamination on the surfaces contacting the film within the manufacturing line is the key culprit for exacerbating surface defect formation. The project is split into three distinct parts that all aimed to deliver a deeper understanding of this problem. The first stage of this work was to characterise the debris found on the manufacturing line to confirm the hypothesised formation pathways. Debris was analysed using a variety of analytical techniques and found it to be primarily composed of the products of PET hydrolytic and oxidative degradation. Next, this work measured the adhesive forces present between the interacting surfaces on the line and aimed to recommend an appropriate cleaning strategy based on an understanding of these interactions. The adhesive force was measured by colloidal probe atomic force microscopy, but no consistent results were found. This is hypothesised to be due to the contributions of surface roughness and humidity making repeatable results a challenge to acquire. Finally, this work aimed to understand how the presence of contamination impacts surface defect formation. New lab-based models for scratch modelling at the micro-scale and for creating pseudo-dirtied surfaces were developed. Topographical and friction measurements revealed that contamination was affecting the frictional properties of the rollers by modifications to both topography and surface energy of the surfaces. Overall, this work was able to solidify and unify much of the historical and anecdotal hypotheses within DuPont Teijin Films of how contamination plays a role in surface defect formation. Armed with this understanding now allows the business to move towards solutions that target the root of the problem

The use and predictive performance of the Peninsula Health Falls Risk Assessment Tool (PH-FRAT) in 25 residential aged care facilities : a retrospective cohort study using routinely collected data

Background: The Peninsula Health Falls Risk Assessment Tool (PH-FRAT) is a validated and widely applied tool in residential aged care facilities (RACFs) in Australia. However, research regarding its use and predictive performance is limited. This study aimed to determine the use and performance of PH-FRAT in predicting falls in RACF residents. Methods: A retrospective cohort study using routinely-collected data from 25 RACFs in metropolitan Sydney, Australia from Jul 2014-Dec 2019. A total of 5888 residents aged ≥65 years who were assessed at least once using the PH-FRAT were included in the study. The PH-FRAT risk score ranges from 5 to 20 with a score > 14 indicating fallers and ≤ 14 non-fallers. The predictive performance of PH-FRAT was determined using metrics including area under receiver operating characteristics curve (AUROC), sensitivity, specificity, sensitivityEvent Rate(ER) and specificityER. Results: A total of 27,696 falls were reported over 3,689,561 resident days (a crude incident rate of 7.5 falls /1000 resident days). A total of 38,931 PH-FRAT assessments were conducted with a median of 4 assessments per resident, a median of 43.8 days between assessments, and an overall median fall risk score of 14. Residents with multiple assessments had increased risk scores over time. The baseline PH-FRAT demonstrated a low AUROC of 0.57, sensitivity of 26.0% (sensitivityER 33.6%) and specificity of 88.8% (specificityER 82.0%). The follow-up PH-FRAT assessments increased sensitivityER values although the specificityER decreased. The performance of PH-FRAT improved using a lower risk score cut-off of 10 with AUROC of 0.61, sensitivity of 67.5% (sensitivityER 74.4%) and specificity of 55.2% (specificityER 45.6%). Conclusions: Although PH-FRAT is frequently used in RACFs, it demonstrated poor predictive performance raising concerns about its value. Introducing a lower PH-FRAT cut-off score of 10 marginally enhanced its predictive performance. Future research should focus on understanding the feasibility and accuracy of dynamic fall risk predictive tools, which may serve to better identify residents at risk of falls

The use of predictive fall models for older adults receiving aged care, using routinely collected electronic health record data : a systematic review

Background: Falls in older adults remain a pressing health concern. With advancements in data analytics and increasing uptake of electronic health records, developing comprehensive predictive models for fall risk is now possible. We aimed to systematically identify studies involving the development and implementation of predictive falls models which used routinely collected electronic health record data in home-based, community and residential aged care settings. Methods: A systematic search of entries in Cochrane Library, CINAHL, MEDLINE, Scopus, and Web of Science was conducted in July 2020 using search terms relevant to aged care, prediction, and falls. Selection criteria included English-language studies, published in peer-reviewed journals, had an outcome of falls, and involved fall risk modelling using routinely collected electronic health record data. Screening, data extraction and quality appraisal using the Critical Appraisal Skills Program for Clinical Prediction Rule Studies were conducted. Study content was synthesised and reported narratively. Results: From 7,329 unique entries, four relevant studies were identified. All predictive models were built using different statistical techniques. Predictors across seven categories were used: demographics, assessments of care, fall history, medication use, health conditions, physical abilities, and environmental factors. Only one of the four studies had been validated externally. Three studies reported on the performance of the models. Conclusions: Adopting predictive modelling in aged care services for adverse events, such as falls, is in its infancy. The increased availability of electronic health record data and the potential of predictive modelling to document fall risk and inform appropriate interventions is making use of such models achievable. Having a dynamic prediction model that reflects the changing status of an aged care client is key to this moving forward for fall prevention interventions

Domestic horses (Equus caballus) prefer to approach humans displaying a submissive body posture rather than a dominant body posture

Signals of dominance and submissiveness are central to conspecific communication in many species. For domestic animals, sensitivities to these signals in humans may also be beneficial. We presented domestic horses with a free choice between two unfamiliar humans, one adopting a submissive and the other a dominant body posture, with vocal and facial cues absent. Horses had previously been given food rewards by both human demonstrators, adopting neutral postures, to encourage approach behaviour. Across four counterbalanced test trials, horses showed a significant preference for approaching the submissive posture in both the first trial and across subsequent trials, and no individual subject showed an overall preference for dominant postures. There was no significant difference in latency to approach the two postures. This study provides novel evidence that domestic horses may spontaneously discriminate between, and attribute communicative significance to, human body postures of dominance; and further, that familiarity with the signaller is not a requirement for this response. These findings raise interesting questions about the plasticity of social signal perception across the species barrier

Assessing Aerosol Mixed Layer Heights from the NASA LaRC Airborne HSRL During the DISCOVER-AQ Field Campaigns

No abstract availabl

Analysis of Qa-1bPeptide Binding Specificity and the Capacity of Cd94/Nkg2a to Discriminate between Qa-1–Peptide Complexes

The major histocompatibility complex class Ib protein, Qa-1b, serves as a ligand for murine CD94/NKG2A natural killer (NK) cell inhibitory receptors. The Qa-1b peptide-binding site is predominantly occupied by a single nonameric peptide, Qa-1 determinant modifier (Qdm), derived from the leader sequence of H-2D and L molecules. Five anchor residues were identified in this study by measuring the peptide-binding affinities of substituted Qdm peptides in experiments with purified recombinant Qa-1b. A candidate peptide-binding motif was determined by sequence analysis of peptides eluted from Qa-1 that had been folded in the presence of random peptide libraries or pools of Qdm derivatives randomized at specific anchor positions. The results indicate that Qa-1b can bind a diverse repertoire of peptides but that Qdm has an optimal primary structure for binding Qa-1b. Flow cytometry experiments with Qa-1b tetramers and NK target cell lysis assays demonstrated that CD94/NKG2A discriminates between Qa-1b complexes containing peptides with substitutions at nonanchor positions P4, P5, or P8. Our findings suggest that it may be difficult for viruses to generate decoy peptides that mimic Qdm and raise the possibility that competitive replacement of Qdm with other peptides may provide a novel mechanism for activation of NK cells

Contribution of Intrinsic Reactivity of the HIV-1 Envelope Glycoproteins to CD4-Independent Infection and Global Inhibitor Sensitivity

Human immunodeficiency virus (HIV-1) enters cells following sequential activation of the high-potential-energy viral envelope glycoprotein trimer by target cell CD4 and coreceptor. HIV-1 variants differ in their requirements for CD4; viruses that can infect coreceptor-expressing cells that lack CD4 have been generated in the laboratory. These CD4-independent HIV-1 variants are sensitive to neutralization by multiple antibodies that recognize different envelope glycoprotein epitopes. The mechanisms underlying CD4 independence, global sensitivity to neutralization and the association between them are still unclear. By studying HIV-1 variants that differ in requirements for CD4, we investigated the contribution of CD4 binding to virus entry. CD4 engagement exposes the coreceptor-binding site and increases the “intrinsic reactivity” of the envelope glycoproteins; intrinsic reactivity describes the propensity of the envelope glycoproteins to negotiate transitions to lower-energy states upon stimulation. Coreceptor-binding site exposure and increased intrinsic reactivity promote formation/exposure of the HR1 coiled coil on the gp41 transmembrane glycoprotein and allow virus entry upon coreceptor binding. Intrinsic reactivity also dictates the global sensitivity of HIV-1 to perturbations such as exposure to cold and the binding of antibodies and small molecules. Accordingly, CD4 independence of HIV-1 was accompanied by increased susceptibility to inactivation by these factors. We investigated the role of intrinsic reactivity in determining the sensitivity of primary HIV-1 isolates to inhibition. Relative to the more common neutralization-resistant (“Tier 2-like”) viruses, globally sensitive (“Tier 1”) viruses exhibited increased intrinsic reactivity, i.e., were inactivated more efficiently by cold exposure or by a given level of antibody binding to the envelope glycoprotein trimer. Virus sensitivity to neutralization was dictated both by the efficiency of inhibitor/antibody binding to the envelope glycoprotein trimer and by envelope glycoprotein reactivity to the inhibitor/antibody binding event. Quantitative differences in intrinsic reactivity contribute to HIV-1 strain variability in global susceptibility to neutralization and explain the long-observed relationship between increased inhibitor sensitivity and decreased entry requirements for target cell CD4

HLA Alleles Associated with Delayed Progression to AIDS Contribute Strongly to the Initial CD8(+) T Cell Response against HIV-1

BACKGROUND: Very little is known about the immunodominance patterns of HIV-1-specific T cell responses during primary HIV-1 infection and the reasons for human lymphocyte antigen (HLA) modulation of disease progression. METHODS AND FINDINGS: In a cohort of 104 individuals with primary HIV-1 infection, we demonstrate that a subset of CD8(+) T cell epitopes within HIV-1 are consistently targeted early after infection, while other epitopes subsequently targeted through the same HLA class I alleles are rarely recognized. Certain HLA alleles consistently contributed more than others to the total virus-specific CD8(+) T cell response during primary infection, and also reduced the absolute magnitude of responses restricted by other alleles if coexpressed in the same individual, consistent with immunodomination. Furthermore, individual HLA class I alleles that have been associated with slower HIV-1 disease progression contributed strongly to the total HIV-1-specific CD8(+) T cell response during primary infection. CONCLUSIONS: These data demonstrate consistent immunodominance patterns of HIV-1-specific CD8(+) T cell responses during primary infection and provide a mechanistic explanation for the protective effect of specific HLA class I alleles on HIV-1 disease progression