scholarly journals Traits for predator selection on Pentaclethra macroloba seeds

2010 ◽  
Vol 8 (4) ◽  
Author(s):  
Gabriela Anhalzer ◽  
Michelle Fournier ◽  
Tim O’Connor ◽  
Louise Stevenson ◽  
Mariel Yglesias
Keyword(s):  
Foraging Strategy ◽  
High Concentration ◽  
Seed Predators ◽  
Tree Population ◽  
Pentaclethra Macroloba ◽  
Optimal Foraging Strategy ◽  
Low Toxicity ◽  
Toxic Alkaloids ◽  
Seed Characteristics ◽  
Selection Of

Pentaclethra macroloba (Fabaceae: Mimosoidea) is a dominant species of canopy tree in Costa Rica’s Caribbean lowlands, constituting up to 40% of the local tree population in some areas. It has been suggested that P. macroloba’s dominance is due in part to low post-dispersal seed depredation, as few terrestrial seed predators can tolerate the high concentration of toxic alkaloids and free amino acids. Seeds are not immune from depredation, however. Several species of parrots and squirrels have been observed depredating pre-dehiscent legumes and may present selective pressure on P. macroloba recruitment. In this study, we assessed depredation patterns in P. macroloba to (1) determine if predators use legume and seed traits to select food items, (2) determine if such patterns represent an optimal foraging strategy for vertebrate predators, and (3) explore potential consequences of depredation on P. macroloba. Seed depredation was not correlated with legume valve side, legume size, seed number, or seed compartment size, though seeds at the distal end of legumes were more often extracted. Depredation patterns do not indicate that seed predators are foraging optimally and may be quickly satiated due to their low toxicity tolerance the abundance of seeds. Despite a lack of predator selection of various legume and seed characteristics, legume damage caused by depredation may interfere with the explosive dehiscence of P. macroloba and constitute a significant recruitment barrier.

The Effects of Shock Vancomycin Concentrations on the Formation of Heteroresistance in Staphylococcus aureus

2020 ◽  
Vol 65 (9-10) ◽  
pp. 3-7
Author(s):  
V. V. Gostev ◽  
Yu. V. Sopova ◽  
O. S. Kalinogorskaya ◽  
M. E. Velizhanina ◽  
I. V. Lazareva ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vitro Selection ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
High Concentration ◽  
Short Term ◽  
High Concentrations ◽  
Selection Of ◽  
Selection Of Resistance ◽  
Test Cultures

Glycopeptides are the basis of the treatment of infections caused by MRSA (Methicillin-Resistant Staphylococcus aureus). Previously, it was demonstrated that antibiotic tolerant phenotypes are formed during selection of resistance under the influence of high concentrations of antibiotics. The present study uses a similar in vitro selection model with vancomycin. Clinical isolates of MRSA belonging to genetic lines ST8 and ST239, as well as the MSSA (ATCC29213) strain, were included in the experiment. Test isolates were incubated for five hours in a medium with a high concentration of vancomycin (50 μg/ml). Test cultures were grown on the medium without antibiotic for 18 hours after each exposure. A total of ten exposure cycles were performed. Vancomycin was characterized by bacteriostatic action; the proportion of surviving cells after exposure was 70–100%. After selection, there was a slight increase in the MIC to vancomycin (MIC 2 μg/ml), teicoplanin (MIC 1.5–3 μg/ml) and daptomycin (MIC 0.25–2 μg/ml). According to the results of PAP analysis, all strains showed an increase in the area under curve depending on the concentration of vancomycin after selection, while a heteroresistant phenotype (with PAP/AUC 0.9) was detected in three isolates. All isolates showed walK mutations (T188S, D235N, E261V, V380I, and G223D). Exposure to short-term shock concentrations of vancomycin promotes the formation of heteroresistance in both MRSA and MSSA. Formation of VISA phenotypes is possible during therapy with vancomycin.

scholarly journals Potential of macrophyte for removing arsenic from aqueous solution

2012 ◽  
Vol 30 (4) ◽  
pp. 683-696 ◽  
Author(s):  
F.P. Guimaraes ◽  
R. Aguiar ◽  
J.A. Oliveira ◽  
J.A.A. Silva ◽  
D. Karam
Keyword(s):  
Aquatic Macrophytes ◽  
Leaf Size ◽  
Mass Gain ◽  
Dry Mass ◽  
Phosphate Deficiency ◽  
Lemna Gibba ◽  
High Concentration ◽  
Carotenoid Synthesis ◽  
High Concentrations ◽  
Selection Of

The potential of three aquatic macrophytes, Azoll caroliniana, Salvinia minima and Lemna gibba, was evaluated in this work aimed at selection of plants to be used in remediation of environments contaminated by arsenic (As). The experiments were carried out in a greenhouse during six days in pots containing Hoagland solution (¼ ionic strength) at As concentrations of 0.5; 2.5 and 5.0 mg L-1. The three species showed greater As accumulation as the concentration of the metalloid in solution increased. However, a reduction was detected in fresh and dry mass gain when the plants were exposed to high As concentrations. The macrophytes showed differences in efficiency of removal of As in solution. A. caroliniana, S. minima and L. gibba accumulated, on average, 0.130; 0.200; and 1.397 mg mDM-1, respectively, when exposed to 5.0 mg L-1 of As. The macrophytes absorbed a greater quantity of As in solution with low phosphate content. The greater As concentration in L. gibba tissues lowered the chlorophyll and carotenoid contents as shown by the high chlorosis incidence. Lemna gibba also exhibited a decrease in leaf size, with the total chlorophyll and carotenoid synthesis not being affected by As in A. caroliniana. This species exhibited purplish leaves with high concentration of anthocyanin, whose presence suggested association to phosphate deficiency. Marginal necrosis occurred on S. minima floating leaves, with the released daughter-plants not showing any visual symptoms during the treatment. The percentage of As removed from the solution decreased when the plants were exposed to high concentrations of the pollutant. Among the three species studied, only L. gibba could be considered an As hyper-accumulator. The use of this plant species for remediation of aquatic environments was shown to be limited and requires further investigation.

scholarly journals Amino Acids as Gustatory Stimuli in the Rat

1962 ◽  
Vol 45 (4) ◽  
pp. 681-701 ◽  
Author(s):  
Bruce P. Halpern ◽  
Rudy A. Bernard ◽  
Morley R. Kare
Keyword(s):  
Amino Acids ◽  
Neural Activity ◽  
Receptor Site ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
High Concentration ◽  
Low Concentration ◽  
Common Receptor ◽  
Amino Acid Solutions ◽  
Selection Of

Neural activity in intact chorda tympani nerve of rats was studied with an electronic summator. Neural activity increased when amino acid solutions 0.01 M or above passed over the tongue. Response magnitude, at concentrations close to solubility limits for the amino acids tested, was: DL-methionine < DL-tryptophan < DL-valine < DL-alanine < glycine < 0.1 M NaCl. Maximum response magnitudes to 1 M D-, and 1.2 M DL-alanine, and 1.5 M glycine developed in 1 to 3 minutes. Following such stimulation, a 63 per cent reduction in response to 0.1 M NaCl occurred 60 minutes after the first stimulation (medians). The depression was still present 20 hours later. Responses to glycine and alanine were not depressed. Amino acids vs. water preferences were investigated. With ascending concentration sequences, rats selected low concentration DL- and L-alanine and glycine; accepted D-, L-, and DL-tryptophan and low concentration DL-methionine; and rejected high concentration glycine, DL-alanine, and DL-methionine. Descending sequences showed depressed and delayed selection of glycine and DL-alanine, and DL-methionine and D- and L-tryptophan rejection. Both groups rejected DL-valine. It is concluded that glycine and alanine receptor effects differ from those of NaCl, but that all three compounds may affect a common receptor site. Prior exposure to amino acids may modify subsequent neural and/or behavioral responses.

scholarly journals A Few Experimental Suggestions Using Minerals to Obtain Peptides with a High Concentration of L-Amino Acids and Protein Amino Acids

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2046
Author(s):  
Dimas A. M. Zaia ◽  
Cássia Thaïs B. V. Zaia
Keyword(s):  
Amino Acids ◽  
Rna World ◽  
High Concentration ◽  
Protein World ◽  
Protein Amino Acids ◽  
Hydrothermal Environment ◽  
World Hypothesis ◽  
Prebiotic Earth ◽  
Hydrothermal Environments ◽  
Selection Of

The peptides/proteins of all living beings on our planet are mostly made up of 19 L-amino acids and glycine, an achiral amino acid. Arising from endogenous and exogenous sources, the seas of the prebiotic Earth could have contained a huge diversity of biomolecules (including amino acids), and precursors of biomolecules. Thus, how were these amino acids selected from the huge number of available amino acids and other molecules? What were the peptides of prebiotic Earth made up of? How were these peptides synthesized? Minerals have been considered for this task, since they can preconcentrate amino acids from dilute solutions, catalyze their polymerization, and even make the chiral selection of them. However, until now, this problem has only been studied in compartmentalized experiments. There are separate experiments showing that minerals preconcentrate amino acids by adsorption or catalyze their polymerization, or separate L-amino acids from D-amino acids. Based on the [GADV]-protein world hypothesis, as well as the relative abundance of amino acids on prebiotic Earth obtained by Zaia, several experiments are suggested. The main goal of these experiments is to show that using minerals it is possible, at least, to obtain peptides whose composition includes a high quantity of L-amino acids and protein amino acids (PAAs). These experiments should be performed using hydrothermal environments and wet/dry cycles. In addition, for hydrothermal environment experiments, it is very important to use one of the suggested artificial seawaters, and for wet/dry environments, it is important to perform the experiments in distilled water and diluted salt solutions. Finally, from these experiments, we suggest that, without an RNA world or even a pre genetic world, a small peptide set could emerge that better resembles modern proteins.

Long- versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats and the consequences for prey selection

1985 ◽  
Vol 63 (11) ◽  
pp. 2507-2515 ◽  
Author(s):  
Robert M. R. Barclay
Keyword(s):  
Short Range ◽  
Prey Availability ◽  
Prey Selection ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Lasiurus Cinereus ◽  
Echolocation Calls ◽  
Straight Line ◽  
Lasionycteris Noctivagans ◽  
Selection Of

Habitat use, temporal activity, foraging behaviour, and prey selection of hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) were studied at Delta Marsh, Manitoba. Bat activity was assessed by monitoring echolocation calls with ultrasonic detectors. Prey availability was determined using sticky and Malaise traps and dietary information was obtained from fecal analysis. Both species were active all night and foraged primarily in the lee of a narrow forested ridge. Lasionycteris noctivagans foraged in a manner that indicates that it detects and pursues prey over short distances. These bats fly slowly, are highly manoeuverable, and were commonly observed feeding on swarms of insects in small clearings. They use echolocation calls that support the notion of a short-range foraging strategy and feed opportunistically on whatever insects are available. Lasiurus cinereus, on the other hand, uses a long-range prey detection and pursuit foraging strategy. They fly rapidly along straight line paths in open areas and use echolocation calls designed to detect insects at a distance. The diet consists primarily of large insects (moths, beetles, and dragonflies), but the bats nonetheless feed opportunistically. The foraging strategy likely restricts the availability and profitability of small insects as prey.

Prestige, taboo, and sustainability: predicting wildlife population trajectories in indigenous commerce

2007 ◽  
Vol 13 (1) ◽  
pp. 4 ◽  
Author(s):  
Clark. S. Monson ◽  
Paul Alan Cox
Keyword(s):  
Foraging Strategy ◽  
Conservation Strategy ◽  
Flying Foxes ◽  
Wildlife Population ◽  
Indigenous Conservation ◽  
Optimal Foraging Strategy ◽  
Negative Impacts ◽  
Extinction Model ◽  
Over Exploitation

Commercial traffic in plants and animals has led to severe declines for some species, while others have experienced few if any negative impacts. Given the uncertainty regarding which species are likely to be adversely affected by monetized trade, it would be useful to have a model that could predict wildlife population trajectories of wild-gathered species subsequent to commercialization. We suggest that the indigenous conservation strategy of "taboo" offers important insights into identifying species that are susceptible to over-exploitation through commercial traffic. We describe an economic conservation/extinction model based on the dual concepts of taboo and optimal foraging strategy and examine the model through a detailed case study of vulnerability to perturbation in the case of commercial traffic in Pacific island flying foxes. We suggest that tile virtual eradication of flying foxes from the island of Guam during the Twentieth Century resulted from a cultural predilection among the indigenous Chamorro people for consuming flying foxes coupled with the cultural loss of the traditional taboo conservation system on the island.

scholarly journals Saccadic Momentum and Facilitation of Return Saccades Contribute to an Optimal Foraging Strategy

2013 ◽  
Vol 9 (1) ◽  
pp. e1002871 ◽  
Author(s):  
Niklas Wilming ◽  
Simon Harst ◽  
Nico Schmidt ◽  
Peter König
Keyword(s):  
Optimal Foraging ◽  
Foraging Strategy ◽  
Optimal Foraging Strategy ◽  
Saccadic Momentum

scholarly journals Habitat selection of woodchat shrikesLanius senatorduring spring stopover is related to foraging strategy

2016 ◽  
pp. zow079 ◽  
Author(s):  
Danai Papageorgiou ◽  
Christos Barboutis ◽  
Christina Kassara ◽  
Sinos Giokas
Keyword(s):  
Habitat Selection ◽  
Foraging Strategy ◽  
Spring Stopover ◽  
Selection Of

Physical Modeling of Combined Forced and Natural Convection in Wet Geothermal Formations

1976 ◽  
Vol 98 (2) ◽  
pp. 213-220 ◽  
Author(s):  
V. E. Schrock ◽  
A. D. K. Laird
Keyword(s):  
Physical Modeling ◽  
Geothermal Energy ◽  
Laboratory Model ◽  
High Concentration ◽  
Efficient Utilization ◽  
Well Location ◽  
New Energy ◽  
Mass Flows ◽  
Disposal Problem ◽  
Selection Of

Wet geothermal formations or reservoirs are of great current interest as a new energy source. Such formations have the potential for large quantities of energy at temperatures of interest for power production and other uses. In these reservoirs the ground water usually contains dissolved solids in such high concentration as to pose a serious disposal problem. For this reason and also to maintain the water table, in most cases, the water will be reinjected into the reservoir after the useful energy has been extracted. Efficient utilization of the potential of a given reservoir requires optimum location of costly producing and reinjection wells. Selection of well location must be based upon an understanding of the heat and mass flows within the reservoir. In this paper, we present some general considerations for physical modeling as well as the results obtained from a laboratory model having two wells to simulate a geothermal energy extraction loop.

Ecology of the Asian elephant in southern India. II. Feeding habits and crop raiding patterns

1990 ◽  
Vol 6 (1) ◽  
pp. 33-53 ◽  
Author(s):  
R. Sukumar
Keyword(s):  
Feeding Habits ◽  
Natural Habitat ◽  
Foraging Strategy ◽  
Dry Season ◽  
Southern India ◽  
Crop Raiding ◽  
Wet Season ◽  
Seasonal Movement ◽  
Food Requirement ◽  
Optimal Foraging Strategy

ABSTRACTThe Asian elephant's foraging strategy in its natural habitat and in cultivation was studied in southern India during 1981–83. Though elephants consumed at least 112 plant species in the study area, about 85% of their diet consisted of only 25 species from the order Malvales and the families Leguminosae, Palmae, Cyperaceae and Gramineae. Alteration between a predominantly browse diet during the dry season with a grass diet during the early wet season was related to the seasonally changing protein content of grasses.Crop raiding, which was sporadic during the dry season, gradually increased with more area being cultivated with the onset of rains. Raiding frequency reached a peak during October-December, with some villages being raided almost every night, when finger millet (Eleusine coracana) was cultivated by most farmers. The monthly frequency of raiding was related to the seasonal movement of elephant herds and to the size of the enclave. Of their total annual food requirement, adult bull elephants derived an estimated 9.3% and family herds 1.7% in quantity from cultivated land. Cultivated cereal and millet crops provided significantly more protein, calcium and sodium than the wild grasses. Ultimately, crop raiding can be thought of as an extension of the elephant's optimal foraging strategy.

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