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1.
Summary Several predictions of central place foraging theory were tested. As predicted, beavers foraged more selectively at increasing distance from the central place. With increasing distance from the river's edge, beavers cut fewer branches and deleted small branches from their diet. Large branches were favored at all distances, which differs from patterns observed in previous studies of beaver foraging. This difference, however, is expected and supports Schoener's (1979) predictions which are based on differences between provisioning costs and item size.The selective harvesting of branches predicted by foraging theory affects plant growth form and may influence plant reproductive patterns. High rates of branch removal caused cottonwoods to develop a shrubby architecture. The importance of selective branch choice by beavers on patterns of cottonwood reproduction (i.e., delayed sexual maturity and induced cloning) is discussed. 相似文献
2.
Kayleigh M. Hansford Sara L. Gandy Emma L. Gillingham Liz McGinley Benjamin Cull Colin Johnston Matthew Catton Jolyon M. Medlock 《Medical and veterinary entomology》2023,37(1):152-163
Tick-borne disease risk is intrinsically linked to the distribution of tick vector species. To assess risk and anticipate disease emergence, an understanding of tick distribution, host associations, and seasonality is needed. This can be achieved, to some extent, using passive surveillance supported by engagement with the public, animal health, and public health experts. The Tick Surveillance Scheme (TSS) collects data and maps tick distribution across the United Kingdom (UK). Between 2017 and 2020, 3720 tick records were received and 39 tick species were detected. Most records were acquired in the UK, with a subset associated with recent overseas travel. The dominant UK acquired species was Ixodes ricinus (Ixodida: Ixodidae, Linnaeus), the main vector of Lyme borreliosis. Records peaked during May and June, highlighting a key risk period for tick bites. Other key UK species were detected, including Dermacentor reticulatus (Ixodida: Ixodidae, Fabricius) and Haemaphysalis punctata (Ixodida: Ixodidae, Canestrini & Fanzago) as well as several rarer species that may present novel tick-borne disease risk to humans and other animals. Updated tick distribution maps highlight areas in the UK where tick exposure has occurred. There is evidence of increasing human tick exposure over time, including during the COVID-19 pandemic, but seasonal patterns remain unchanged. 相似文献
3.
Jean H. Langenheim Craig E. Foster Robert B. McGinley 《Biochemical Systematics and Ecology》1980,8(4):385-396
The hypotheses that quantitative variation in leaf resins in the leguminous genus Hymenaea may partially be a response to insect predation was tested in feeding experiments with the generalist herbivore, the beet armyworm, Spodoptera exigua Hübn (Noctuidae). Leaf resins of all Hymenaea species are comprised of essentially the same suite of sesquiterpene hydrocarbons, but discrete quantitative patterns have been classified as Compositional Types based on the amounts of major components. In this work pure extracts of leaf resins of Type I (high - and β-selinene), Type II (intermediate amounts of -and β-selinene and caryophyllene) and Type III (high caryophyllene) were incorporated into an artificial diet for the insects at 1 and 3.2% (dry wt). Resin Type treatments produced differential dose-dependent effects on growth rate (lower larval weights and increased time to pupation) and in mortality. More significant inhibitory effects occurred in Compositional Types with a predominance of a single compared (i.e. Types I and III). Significantly higher mortality occurring in Type III treatments suggests that caryophllene may have higher potential toxicity than - and β-selinene for S. exigua. These experiments indicate that feeding by generalist herbivores could be a factor determining quantitative compositional variation: (a) among populations; (b) during the development of leaves; (c) in the spatial distribution within the leaves; and (d) between parent tree and seedling progeny. 相似文献
4.
Hansford Kayleigh M. McGinley Liz Wilkinson Samantha Gillingham Emma L. Cull Ben Gandy Sara Carter Daniel P. Vaux Alexander G. C. Richards Simon Hayes Alister Medlock Jolyon M. 《Experimental & applied acarology》2021,84(3):593-606
Experimental and Applied Acarology - Assessing the risk of tick-borne disease in areas with high visitor numbers is important from a public health perspective. Evidence suggests that tick presence,... 相似文献
5.
6.
The use of architectural and morphological characteristics of cells for establishing prognostic indicators by which individual
pathologies are assigned grade and stage is a well-accepted practice. Advances in automated micro- and macroscopic image acquisition
and digital image analysis have created new opportunities in the field of prognostic assessment; but, one area in experimental
pathology, animal models for colon cancer, has not taken advantage of these opportunities. This situation is primarily due
to the methods available to evaluate the colon of the rodent for the presence of premalignant and malignant pathologies. We
report a new method for the excision and processing of the entire colon of the rat and illustrate how this procedure permitted
the quantitative assessment of aberrant crypt foci (ACF), a premalignant colon pathology, for characteristics consistent with
progression to malignancy. ACF were detected by methylene blue staining and subjected to quantitative morphometric analysis.
Colons were then restained with high iron diamine–alcian blue for assessment of mucin depletion using an image overlay to
associate morphometric data with mucin depletion. The subsequent evaluation of ACF for beta-catenin staining is also demonstrated.
The methods described are particularly relevant to the screening of compounds for cancer chemopreventive activity. 相似文献
7.
Heterodimerization of the alpha and beta isoforms of the human thromboxane receptor enhances isoprostane signaling 总被引:1,自引:0,他引:1
Wilson SJ McGinley K Huang AJ Smyth EM 《Biochemical and biophysical research communications》2007,352(2):397-403
Isoprostanes are free radical catalyzed products of arachidonic acid that are elevated in pro-oxidant disease states. Two isoprostanes, 8-isoprostaglandin F(2alpha) (iPF(2alpha)III) and 8-isoprostaglandin E2 (iPE2III), act at the receptor for thromboxane A2 (the TP) to mediate pro-atherogenic effects in vivo. We confirmed dimerization of the human TP isoforms, TPalpha and TPbeta, and determined the impact on isoprostane signaling. No overt changes in ligand binding at the TP were observed as a result of TPalpha/TPbeta coexpression. The response to iPF(2alpha)III or iPE2III was enhanced in HEK293 cells stably coexpressing TPalpha and TPbeta, as measured by inositol phosphate generation or intracellular calcium mobilization, relative to cells expressing TPalpha or TPbeta individually. In contrast, the response to traditional thromboxane analogs was unaltered. Augmented isoprostane signaling was similarly observed in HEK 293 cell transiently transfected with TPalpha and TPbeta. These results indicate that TPalpha/TPbeta dimerization enhances isoprostane-mediated signal transduction. 相似文献
8.
McGinley CM Jacquot C van der Donk WA 《Bioorganic & medicinal chemistry letters》2007,17(14):4049-4052
The mechanism by which prostaglandin synthase converts arachidonic acid to prostaglandin G(2), creating five new chiral centers in the process, is still incompletely understood. The first radical intermediate has been characterized by EPR spectroscopy but subsequent proposed intermediates have not succumbed to detection. We report the synthesis of 7-thiaarachidonic acid designed to stabilize one of the proposed radical intermediates, which may allow its detection. 相似文献
9.
Background
Rodent models have been used extensively to study mammary gland development and for studies of toxicology and carcinogenesis. Mammary gland gross morphology can visualized via the excision of intact mammary gland chains following fixation and staining with carmine using a tissue preparation referred to as a whole mount. Methods are described for the automated collection of digital images from an entire mammary gland whole mount and for the interrogation of digital data using a "masking" technique available with Image-Pro® plus image analysis software (Mediacybernetics. Silver Spring, MD).Results
Parallel to mammographic analysis in humans, measurements of rodent mammary gland density were derived from area-based or volume-based algorithms and included: total circumscribed mammary fat pad mass, mammary epithelial mass, and epithelium-free fat pad mass. These values permitted estimation of absolute mass of mammary epithelium as well as breast density. The biological plausibility of these measurements was evaluated in mammary whole mounts from rats and mice. During mammary gland development, absolute epithelial mass increased linearly without significant changes in mammographic density. Treatment of rodents with tamoxifen, 9-cis-retinoic acid, or ovariectomy, and occurrence of diet induced obesity decreased both absolute epithelial mass and mammographic density. The area and volumetric methods gave similar results.Conclusions
Digital image analysis can be used for screening agents for potential impact on reproductive toxicity or carcinogenesis as well as for mechanistic studies, particularly for cumulative effects on mammary epithelial mass as well as translational studies of mechanisms that explain the relationship between epithelial mass and cancer risk.10.
Chin CH Kirkness JP Patil SP McGinley BM Smith PL Schwartz AR Schneider H 《Journal of applied physiology (Bethesda, Md. : 1985)》2012,112(3):403-410
Defective structural and neural upper airway properties both play a pivotal role in the pathogenesis of obstructive sleep apnea. A more favorable structural upper airway property [pharyngeal critical pressure under hypotonic conditions (passive Pcrit)] has been documented for women. However, the role of sex-related modulation in compensatory responses to upper airway obstruction (UAO), independent of the passive Pcrit, remains unclear. Obese apneic men and women underwent a standard polysomnography and physiological sleep studies to determine sleep apnea severity, passive Pcrit, and compensatory airflow and respiratory timing responses to prolonged periods of UAO. Sixty-two apneic men and women, pairwise matched by passive Pcrit, exhibited similar sleep apnea disease severity during rapid eye movement (REM) sleep, but women had markedly less severe disease during non-REM (NREM) sleep. By further matching men and women by body mass index and age (n = 24), we found that the lower NREM disease susceptibility in women was associated with an approximately twofold increase in peak inspiratory airflow (P = 0.003) and inspiratory duty cycle (P = 0.017) in response to prolonged periods of UAO and an ~20% lower minute ventilation during baseline unobstructed breathing (ventilatory demand) (P = 0.027). Thus, during UAO, women compared with men had greater upper airway and respiratory timing responses and a lower ventilatory demand that may account for sex differences in sleep-disordered breathing severity during NREM sleep, independent of upper airway structural properties and sleep apnea severity during REM sleep. 相似文献