University of Maine

About: University of Maine is a education organization based out in Orono, Maine, United States. It is known for research contribution in the topics: Population & Ice sheet. The organization has 8637 authors who have published 16932 publications receiving 590124 citations. The organization is also known as: University of Maine at Orono.

Activity of antimicrobial skin peptides from ranid frogs against Batrachochytrium dendrobatidis, the chytrid fungus associated with global amphibian declines

Abstract: Accumulating evidence suggests that a chytrid fungus, Batrachochytrium dendrobatidis, is responsible for recent declines in amphibian populations in Australia, Central America, Europe, and North America. Because the chytrid infects the keratinized epithelium of the skin, we investigated the possible role of antimicrobial peptides produced in the skin as inhibitors of infection and growth. We show here that 10 peptides representing eight families of peptides derived from North American ranid frogs can effectively inhibit growth of this chytrid. The peptides are members of the ranatuerin-1, ranatuerin-2, esculentin-1, esculentin-2, brevinin-2, temporin, palustrin-3, and ranalexin families. All the tested peptides inhibit growth of mature fungal cells at concentrations above 25 microM, and some of them inhibit at concentrations as low as 2 microM. A comparison of the sensitivity of infectious zoospores with that of mature cells showed that the zoospores are inhibited at significantly lower concentrations of peptides. To determine whether cold temperature interferes with the inhibitory effects of these peptides, we tested their effectiveness at both 22 and 10 degrees C. Although the peptides inhibit at both temperatures, they appear to be more effective against zoospores at the lower temperature. These results suggest that the ranid frogs have, within their repertoire of antimicrobial substances, a number of skin peptides that should be a deterrent to chytrid infection. This may provide some natural resistance to infection, but if environmental factors inhibit the synthesis and release of the skin peptides, the pathogen could gain the advantage.

A Comparison of Conjoint Analysis Response Formats

Abstract: A split-sample design is used to cvnluatc the convergent validity of three rcsponsc formats used in conjoint analysis experiments. WC investigate whether recoding rating data to rankings and chooscone formats. and recoding rranking data to choose one. result in structural models and welfare estimates that arc statistically indistinguishalde from estimates based on ranking or C~OOSC-one questions. Our results indicate that convergent validity of ratings, ranks, and choose one is not established. in addition, WC: find that people frequently use “ties” in rcsponscs to rating questions. and that the option not to choose any of the alternatives (“opt-out”) affects some prefcrcnce cstimales.

Abrupt vegetation and climate changes during the last glacial maximum and last termination in the chilean lake district: a case study from canal de la puntilla (41¡s)

Abstract: Multiple overlapping and replicate pollen stratigraphies from Canal de la Puntilla (40°57'09S, 72°54'18W, 120 m elevation) reveal that a Nothofagus dombeyi-type parkland occupied the Valle Central of the Chilean Lake District during the portion of the Last Glacial Maximum between 20,200 and about 14,600 14 C yr BP. Dominating this landscape was Nothofagus dombeyi-type and Gramineae, accompanied by taxa commonly found today in Subantarctic environments and above the Andean tree-line in the Lake District (Perezia-type, Valeriana, and Huperzia selago), along with cushion bog taxa characteristic of Magellanic Moorlands (Donatia fascicularis and Astelia pumila). Within this open landscape Nothofagus dombeyi-type expanded between 20,200 and 15,800 14 C yr BP, interrupted by a brief reversal between 19,200 and 18,800 14 C yr BP and followed by a prominent increase in Gramineae pollen between 15.800 and about 14,600 14 C yr BP. A major rise of Nothofagus dombeyi-type began at about 14,600 14 C yr BP, followed by decline in non-arboreal taxa and a remarkable expansion of North Patagonian Rain Forest taxa in pulses centered at 14,200 and 13,000 14 C yr BP. Podocarpus nubigena expanded between 12,200 and 9800 14 C yr BP, along with increases in Misodendrum and Maytenus disticha-type between 11,000 and 9800 14 C yr BP. Paleovegetation records suggest that mean annual temperature was 6-7°C colder than at present during the coldest episodes between 20,200 and about 14,600 14 C yr BP, with twice the modem annual precipitation between 20,200 and 13,000 14 C yr BP, suggesting a northward shift and intensification of westerly stormtracks. Slight climate warming occurred between 20,200 and 15,800 14 C yr BP, interrupted by cooling events at 19,200 and 15,800 14 C yr BP. The initial warming of the last termination started at 14,600 14 C yr BP, followed by wanning pulses at 14,200 and 13,000 14 C yr BP. These events brought glacial conditions to a cool-temperate climate, slightly cooler and welter than modern climate, accounting for a total temperature recovery of ≥5°C by about 13,000 14 C yr BP. A general reversal in trend is inferred with cooling events at 12,200 and 11,000 14 C yr BP.

Estimating rates of biologically driven coral reef framework production and erosion: a new census-based carbonate budget methodology and applications to the reefs of Bonaire

Abstract: Census-based approaches can provide important measures of the ecological processes controlling reef carbonate production states. Here, we describe a rapid, non-destructive approach to carbonate budget assessments, termed ReefBudget that is census-based and which focuses on quantifying the relative contributions made by different biological carbonate producer/eroder groups to net reef framework carbonate production. The methodology is presently designed only for Caribbean sites, but has potential to be adapted for use in other regions. Rates are calculated using data on organism cover and abundance, combined with annual extension or production rate measures. Set against this are estimates of the rates at which bioeroding species of fish, urchins and internal substrate borers erode reef framework. Resultant data provide a measure of net rates of biologically driven carbonate production (kg CaCO3 m−2 year−1). These data have potential to be integrated into ecological assessments of reef state, to aid monitoring of temporal (same-site) changes in rates of biological carbonate production and to provide insights into the key ecological drivers of reef growth or erosion as a function of environmental change. Individual aspects of the budget methodology can also be used alongside other census approaches if deemed appropriate for specific study aims. Furthermore, the methodology spreadsheets are user-changeable, allowing local or new process/rate data to be integrated into calculations. Application of the methodology is considered at sites around Bonaire. Highest net rates of carbonate production, +9.52 to +2.30 kg CaCO3 m−2 year−1, were calculated at leeward sites, whilst lower rates, +0.98 to −0.98 kg CaCO3 m−2 year−1, were calculated at windward sites. Data are within the ranges calculated in previous budget studies and provide confidence in the production estimates the methodology generates.

CX3CR1-dependent renal macrophage survival promotes Candida control and host survival

Abstract: Systemic Candida albicans infection causes high morbidity and mortality and is associated with neutropenia; however, the roles of other innate immune cells in pathogenesis are poorly defined. Here, using a mouse model of systemic candidiasis, we found that resident macrophages accumulated in the kidney, the main target organ of infection, and formed direct contacts with the fungus in vivo mainly within the first few hours after infection. Macrophage accumulation and contact with Candida were both markedly reduced in mice lacking chemokine receptor CX3CR1, which was found almost exclusively on resident macrophages in uninfected kidneys. Infected Cx3cr1-/- mice uniformly succumbed to Candida-induced renal failure, but exhibited clearance of the fungus in all other organs tested. Renal macrophage deficiency in infected Cx3cr1-/- mice was due to reduced macrophage survival, not impaired proliferation, trafficking, or differentiation. In humans, the dysfunctional CX3CR1 allele CX3CR1-M280 was associated with increased risk of systemic candidiasis. Together, these data indicate that CX3CR1-mediated renal resident macrophage survival is a critical innate mechanism of early fungal control that influences host survival in systemic candidiasis.