70 research outputs found

    Do wintering conditions drive population trends in semipalmated sandpipers (Calidris pusilla)? Evidence from a corticosterone biomarker

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    Thesis (M.S.) University of Alaska Fairbanks, 2018Some of the most extreme long-distance migrants, Arctic-breeding shorebirds are disproportionately represented in tallies of declining species worldwide. For many shorebirds, including the semipalmated sandpiper (Calidris pusilla), the specific causes and mechanisms behind population declines have not been identified. Stressful conditions affecting birds during wintering are often implicated. Interactions between events and processes occurring in the disparate locations used throughout the annual cycle also may be critical in shaping both individual life histories and population demographics. The main objectives of my graduate research were: a) to examine whether semipalmated sandpipers wintering in specific locations incur differential levels of stress; and b) to test whether stressful conditions may carry over between different stages of an individual's life cycle. Using measurements of corticosterone (the primary avian stress hormone) deposited in winter-grown feathers, I examined the contribution of breeding season and fall migration to winter-incurred stress, and looked for evidence of carryover effects from wintering conditions to spring migration and subsequent reproductive performance. In Chapter 1, I compared the levels of stress exposure of 40 semipalmated sandpipers that bred at five Arctic sites and spent the austral summer in distinct regions (identified via light-sensing geolocators) across their tropical 'wintering' range. I found stress exposure varied by wintering region, and birds using locations along the Atlantic coast of northeastern South America and the Pacific coast of Central America had the highest feather corticosterone levels. I did not find evidence that carryover effects from the breeding season and/or fall migration influenced birds' physiology during winter. In Chapter 2, I investigated whether greater stress exposure during winter might subsequently affect birds during spring migration and/or breeding. I found that geolocator-tracked birds with increased stress levels delayed spring migration and initiated nests later. However, results for a larger dataset (including 254 birds breeding at seven sites across the North American Arctic) suggested low-stress birds nested later. It is possible the larger dataset included replacement clutches that could have confounded relationships with feather corticosterone, as only birds in better condition are likely to re-nest after clutch failure. In addition, I found evidence that stressful wintering conditions carryover to affect reproductive performance: females that accrued high levels of stress during wintering subsequently laid fewer eggs. In confirmed first nests, we found evidence for a clutch size-egg volume tradeoff, with high-stress females producing fewer offspring but potentially investing more in individual offspring. This research represents the first instance of the feather corticosterone technique being used to compare conditions across the wintering range of a calidrid shorebird and reveals specific wintering locations with high levels of stress exposure. This is also the first research that provides a mechanistic perspective on carryover effects between the wintering and breeding stages in a shorebird, through measurements of feather corticosterone. Finally, by showing that poor environmental conditions at wintering sites far from Arctic breeding areas may be detrimental to the reproductive performance of a species with declining populations, this research emphasizes the importance of considering full annual cycles in conservation and research efforts for migratory species

    The Relationship Between Sleep and Health Measures in College Students

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    College students have been known to get little sleep throughout the process of obtaining their degrees. This poor sleep quality has been shown to correlate to higher levels of depression and mental health issues. Additionally, sleep quality in college students is related to various physical variables which are further explored in this study. PURPOSE: The purpose of this study was to examine the relationship between hours of sleep and various health measures of college students. METHODS: This study was a correlational study examining the relationship between hours of sleep and demographic variables of college students. Subjects were recruited from classes at a small, private Texas university. Upon completion of the informed consent subjects were asked to complete a series of questions, one of those being “On average how many hours of sleep per night do you get?” (HrsSleep). After completing the questions resting heart rate (RHR), blood pressure (SysBP and DiaBP), height (Ht), and weight (Wt) were measured. RESULTS: The study consisted of 49 college students (age = 22.76 ± 6.19). There was a significant negative relationship between HrsSleep and Wt (r = -0.46, p = \u3c.001), HrsSleep and SysBP (r = -0.31, p = .03), HrsSleep and DiaBP (r = -0.30, p = .04) and HrsSleep and Ht (r = -0.31, p = .03). There was no significant relationship between HrsSleep and RHR ( r = -0.17, p = .22) and HrsSleep and age (r = 0.14, p = 0.34). CONCLUSION: The study demonstrates that sleep has significant correlations to various health measures in college students. It was found that less sleep is related to higher blood pressure and increased weight. Increased blood pressure and weight can contribute to secondary health conditions that could be experienced by college students. Given the results of this study one way to potentially alleviate these secondary health conditions would be to encourage college students to get more sleep. The research also indicated that taller individuals got less sleep. Obviously, one cannot adjust their height, however, taller college students should be encouraged to make healthy lifestyle choices that foster good sleep habits. In conclusion, the results of this study suggest that getting enough sleep could serve to improve some health measures in college students

    Group B Streptococcus Infection of the Human Extraplacental Membranes.

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    Streptococcus agalactiae (GBS) is the leading cause of infectious neonatal morbidity and mortality in the United States. GBS infections in the gravid female reproductive tract are associated with adverse birth outcomes. The ascending pathway of infection begins with GBS colonization of the vagina, passes through the cervix and uterine cavity where it can cross the extraplacental membranes and infect the fetus. However, the mechanisms by which GBS colonizes and infects the extraplacental membranes remain poorly understood. In addition, environmental toxicant interaction with the innate immune system during pregnancy-related infections remains to be elucidated. In the present thesis, extraplacental membranes cocultured with GBS increased secretion of the antimicrobial peptide human beta defensin (HBD)-2 and killed GBS over time (P < 0.05). Notably, a pattern of localized increased HBD-2 in the amnion of GBS-infected membranes was observed. Interleukin (IL)-1alpha and IL-1beta secreted from choriodecidual tissue was essential for stimulating HBD-2 in the amnion cells. Direct stimulation of amnion cells with live GBS, lipoteichoic acid (LTA), or lipopolysaccharide (LPS) did not increase HBD-2 release. Increases in cytokine release were GBS strain dependent (P < 0.05). GBS recovery from membranes was also GBS strain dependent, with colonizing strains persisting on the choriodecidual side of the membranes. The trichloroethylene (TCE) metabolite S-(1,2)-dichlorovinyl-L-cysteine (DCVC) significantly inhibited pathogen (LTA, LPS, and GBS)-stimulated TNF-alpha release from extraplacental membranes. Both TNF-alpha mRNA expression and protein secretion were inhibited as early as 4 h after initiating co-treatment of tissue punches with DCVC and LTA (P < 0.05). A different TCE metabolite, trichloroacetic acid (10-500 µM), failed to inhibit LTA-stimulated cytokine release from extraplacental membranes. In summary, extraplacental membranes in culture mounted a robust immune response to GBS. Cell-to-cell signaling from the choriodecidua to the amnion was critical for GBS-stimulated HBD-2 in amnion. Host response in the extraplacental membranes was GBS strain specific. The results from the present study provide new insight into the mechanisms of host defense during GBS infection and need to be considered for future treatment and prevention strategies. In addition, pathogen-toxicant interactions should be considered in the current paradigm for increased risk for intrauterine infection.PhDToxicologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/109048/1/boldenow_1.pd

    Combining survey and remotely sensed environmental data to estimate the habitat associations, abundance and distribution of breeding thin-billed prions Pachyptila belcheri and Wilson’s storm-petrels Oceanites oceanicus on a South Atlantic tussac island

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    Small petrels are the most abundant seabirds in the Southern Ocean. However, because they breed in burrows on remote and often densely vegetated islands, their colony sizes and conservation status remain poorly known. To estimate the abundance of these species on Bird Island in the Falkland archipelago, we systematically surveyed their breeding burrow density and occupancy across this near-pristine tussac (Poa flabellata)-covered island. By modelling burrow density as functions of topography and Sentinel 2 satellite-derived Normalised Difference Vegetation Index data, we inferred habitat associations and predicted burrow abundance of the commonest species—Thin-billed Prions (Pachyptila belcheri) and Wilson’s Storm-petrels (Oceanites oceanicus). We estimate that there are 631,000 Thin-billed Prion burrows on the island (95% CI 496,000–904,000 burrows). Assuming that burrow occupancy lies between 12 and 97%, this equates to around 76,000–612,000 breeding pairs, making Bird Island the second or third largest P. belcheri colony in the world, holding approximately 3–27% of the species’ breeding population. We estimate that 8200–9800 (95% CI 5,200–18,300 pairs) pairs of Wilson’s Storm-petrels also breed on the island. Notably, the latter burrowed predominantly under and within tussac pedestals, whereas they are usually assumed to breed in rock cavities. Thin-billed Prions are declining in the Kerguelen archipelago, but their population trends in the Falklands are unknown. Given the wide confidence intervals around our own and other population estimates for these cryptic species, we recommend that their populations should be monitored regularly, at multiple sites.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

    Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds

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    Additional Authors: Bruce Casler; Maureen Christie; Jonathan T. Coleman; Jesse R. Conklin; Willow B. English; H. River Gates; Olivier Gilg; Marie-Andrée Giroux; Ken Gosbell; Chris Hassell; Jim Helmericks; Andrew Johnson; Borgný Katrínardóttir; Kari Koivula; Jean-Francois Lamarre; Johannes Lang; David B. Lank; Nicolas Lecomte; Joe Liebezeit; Vanessa Loverti; Laura McKinnon; Clive Minton; David Mizrahi; Erica Nol; Veli-Matti Pakanen; Johanna Perz; Ron Porter; Jennie Rausch; Jeroen Reneerkens; Nelli Rönkä; Sarah Saalfeld; Nathan Senner; Benoît Sittler; Paul A. Smith; Kristine Sowl; Audrey Taylor; David H. Ward; Stephen YezerinacCitation: Weiser, E.L., R.B. Lanctot, S.C. Brown, J.A. Alves, P.F. Battley, R. Bentzen, J. Bêty, M.A. Bishop, M. Boldenow, L. Bollache, B. Casler, M. Christie, J.T. Coleman, J.R. Conklin, W.B. English, H.R. Gates, O. Gilg, M.-A. Giroux, K. Gosbell, C. Hassell, J. Helmericks, A. Johnson, B. Katrínardóttir, K. Koivula, E. Kwon, J.-F. Lamarre, J. Lang, D.B. Lank, N. Lecomte, J. Liebezeit, V. Loverti, L. McKinnon, C. Minton, D. Mizrahi, E. Nol, V.-M. Pakanen, J. Perz, R. Porter, J. Rausch, J. Reneerkens, N. Rönkä, S. Saalfeld, N. Senner, B. Sittler, P.A. Smith, K. Sowl, A. Taylor, D.H. Ward, S. Yezerinac, and B.K. Sandercock. 2016. Effects of geolocators on hatching success, return rates, breeding movements and change in body mass in 16 species of Arctic-breeding shorebirds. Movement Ecology 4: art12. URL: http://movementecologyjournal.biomedcentral.com/articles/10.1186/s40462-016-0077-6Background: Geolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8–2.0 g total, representing 0.1–3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2–4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26–1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables. Result: We detected negative effects of tags for three small-bodied species. Geolocators reduced annual return rates for two of 23 taxa: by 63 % for semipalmated sandpipers and by 43 % for the arcticola subspecies of dunlin. High resighting effort for geolocator birds could have masked additional negative effects. Geolocators were more likely to negatively affect return rates if the total mass of geolocators and color markers was 2.5–5.8 % of body mass than if tags were 0.3–2.3 % of body mass. Carrying a geolocator reduced nest success by 42 % for semipalmated sandpipers and tripled the probability of partial clutch failure in semipalmated and western sandpipers. Geolocators mounted perpendicular to the leg on a flag had stronger negative effects on nest success than geolocators mounted parallel to the leg on a band. However, parallel-band geolocators were more likely to reduce return rates and cause injuries to the leg. No effects of geolocators were found on breeding movements or changes in body mass. Among-site variation in geolocator effect size was high, suggesting that local factors were important. Conclusions: Negative effects of geolocators occurred only for three of the smallest species in our dataset, but were substantial when present. Future studies could mitigate impacts of tags by reducing protruding parts and minimizing use of additional markers. Investigators could maximize recovery of tags by strategically deploying geolocators on males, previously marked individuals, and successful breeders, though targeting subsets of a population could bias the resulting migratory movement data in some species

    Cellular immune responses in amniotic fluid of women with preterm labor and intraâ amniotic infection or intraâ amniotic inflammation

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    ProblemPreterm birth is commonly preceded by preterm labor, a syndrome that is causally linked to both intraâ amniotic infection and intraâ amniotic inflammation. However, the stereotypical cellular immune responses in these two clinical conditions are poorly understood.Method of studyAmniotic fluid samples (n = 26) were collected from women diagnosed with preterm labor and intraâ amniotic infection (amniotic fluid ILâ 6 concentrations â ¥2.6 ng/mL and culturable microorganisms, n = 10) or intraâ amniotic inflammation (amniotic fluid ILâ 6 concentrations â ¥2.6 ng/mL without culturable microorganisms, n = 16). Flow cytometry was performed to evaluate the phenotype and number of amniotic fluid leukocytes. Amniotic fluid concentrations of classical proâ inflammatory cytokines, type 1 and type 2 cytokines, and Tâ cell chemokines were determined using immunoassays.ResultsWomen with spontaneous preterm labor and intraâ amniotic infection had (a) a greater number of total leukocytes, including neutrophils and monocytes/macrophages, in amniotic fluid; (b) a higher number of total T cells and CD4+ T cells, but not CD8+ T cells or B cells, in amniotic fluid; and (c) increased amniotic fluid concentrations of ILâ 6, ILâ 1β, and ILâ 10, compared to those with intraâ amniotic inflammation. However, no differences in amniotic fluid concentrations of Tâ cell cytokines and chemokines were observed between these two clinical conditions.ConclusionThe cellular immune responses observed in women with preterm labor and intraâ amniotic infection are more severe than in those with intraâ amniotic inflammation, and neutrophils, monocytes/macrophages, and CD4+ T cells are the main immune cells responding to microorganisms that invade the amniotic cavity. These findings provide insights into the intraâ amniotic immune mechanisms underlying the human syndrome of preterm labor.The relative distribution of innate and adaptive immune cell subsets in amniotic fluid of women with preterm labor and intraâ amniotic inflammation. Flow cytometry analysis is shown as a tâ SNE plot.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151891/1/aji13171_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151891/2/aji13171.pd

    Why do avian responses to change in Arctic green-up vary?

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    Global climate change has altered the timing of seasonal events (i.e., phenology) for a diverse range of biota. Within and among species, however, the degree to which alterations in phenology match climate variability differ substantially. To better understand factors driving these differences, we evaluated variation in timing of nesting of eight Arctic-breeding shorebird species at 18 sites over a 23-year period. We used the Normalized Difference Vegetation Index as a proxy to determine the start of spring (SOS) growing season and quantified relationships between SOS and nest initiation dates as a measure of phenological responsiveness. Among species, we tested four life history traits (migration distance, seasonal timing of breeding, female body mass, expected female reproductive effort) as species-level predictors of responsiveness. For one species (Semipalmated Sandpiper), we also evaluated whether responsiveness varied across sites. Although no species in our study completely tracked annual variation in SOS, phenological responses were strongest for Western Sandpipers, Pectoral Sandpipers, and Red Phalaropes. Migration distance was the strongest additional predictor of responsiveness, with longer-distance migrant species generally tracking variation in SOS more closely than species that migrate shorter distances. Semipalmated Sandpipers are a widely distributed species, but adjustments in timing of nesting relative to variability in SOS did not vary across sites, suggesting that different breeding populations of this species were equally responsive to climate cues despite differing migration strategies. Our results unexpectedly show that long-distance migrants are more sensitive to local environmental conditions, which may help them to adapt to ongoing changes in climate. climate change, migration, NDVI, nest initiation, phenology, shorebirdspublishedVersio

    A streptococcal lipid toxin induces membrane permeabilization and pyroptosis leading to fetal injury

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    Group B streptococci (GBS) are Gram-positive bacteria that cause infections in utero and in newborns. We recently showed that the GBS pigment is hemolytic and increased pigment production promotes bacterial penetration of human placenta. However, mechanisms utilized by the hemolytic pigment to induce host cell lysis and the consequence on fetal injury are not known. Here, we show that the GBS pigment induces membrane permeability in artificial lipid bilayers and host cells. Membrane defects induced by the GBS pigment trigger K+ efflux leading to osmotic lysis of red blood cells or pyroptosis in human macrophages. Macrophages lacking the NLRP3 inflammasome recovered from pigment-induced cell damage. In a murine model of in utero infection, hyperpigmented GBS strains induced fetal injury in both an NLRP3 inflammasome-dependent and NLRP3 inflammasome-independent manner. These results demonstrate that the dual mechanism of action of the bacterial pigment/lipid toxin leading to hemolysis or pyroptosis exacerbates fetal injury and suggest that preventing both activities of the hemolytic lipid is likely critical to reduce GBS fetal injury and preterm birth

    A mouse model reproducing the pathophysiology of neonatal group B streptococcal infection

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    Group B streptococcal (GBS) meningitis remains a devastating disease. The absence of an animal model reproducing the natural infectious process has limited our understanding of the disease and, consequently, delayed the development of effective treatments. We describe here a mouse model in which bacteria are transmitted to the offspring from vaginally colonised pregnant females, the natural route of infection. We show that GBS strain BM110, belonging to the CC17 clonal complex, is more virulent in this vertical transmission model than the isogenic mutant BM110∆cylE, which is deprived of hemolysin/cytolysin. Pups exposed to the more virulent strain exhibit higher mortality rates and lung inflammation than those exposed to the attenuated strain. Moreover, pups that survive to BM110 infection present neurological developmental disability, revealed by impaired learning performance and memory in adulthood. The use of this new mouse model, that reproduces key steps of GBS infection in newborns, will promote a better understanding of the physiopathology of GBS-induced meningitis.The authors gratefully acknowledge the help of Encarnaca̧ ̃o Ribeiro for excellent technical assistance, Joana Tavares for assisting with IVIS Lumina LT, Susana Roque for the luminex instrument experiments, the Molecular Microbiology group at i3S for microscope use, and the Portuguese architect and artist Gil Ferreira da Silva for the artworks included in the last figure. This work was supported by funds from Foundation for Science and Technology (FCT), European Regional Development Fund (FEDER) and Compete under project POCI-01-0145-FEDER-016607 (PTDC/IMI-MIC/1049/2014) and from the project NORTE-01-0145-FEDER-000012, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). T.S. and A.M. were supported by Investigador FCT (IF/00875/2012 and IF/00753/2014), POPH and Fundo Social Europeu. E.B.A. and C.C.P. hold postdoctoral fellowships from FCT (PTDC/IMI-MIC/1049/2014 and SFRH/BPD/91962/2012). Ar.F. and P.T.C. were supported by Laboratoire d’Excellence (LABEX) Integrative Biology of Emerging Infectious Diseases (grant ANR-10-LABX-62-IBEID).info:eu-repo/semantics/publishedVersio

    Unexpected diversity in socially synchronized rhythms of shorebirds

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    The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring). The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood. Here we investigate these rhythms in the context of biparental care, a particularly sensitive phase of social synchronization where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within-and between-species diversity in incubation rhythms. Between species, the median length of one parent's incubation bout varied from 1-19 h, whereas period length-the time in which a parent's probability to incubate cycles once between its highest and lowest value-varied from 6-43 h. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or who actively protect their nest against predators. Rhythms entrainable to the 24-h light-dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms.</p
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