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71.
72.
Previous experimental studies of competition among foragers rarely distinguished between exploitation and interference competition.
In many systems this separation is experimentally impossible without interfering with the natural behavior of the animals.
Consequently, these studies can only demonstrate the combined effect of interference and exploitation on the forager’s feeding
rate, namely, it usually decreases in a decelerating rate as a function of density. We suggest here a simple experimental
and statistical procedure that facilitates the separation of the effects of interference from those of exploitation. This
procedure includes manipulation of both predator density and the foraging experiment duration. The statistical analysis is
based on multiple linear regression. The working assumption is that exploitation can be neglected at the beginning of the
foraging experiment because, initially, predators do not experience diminishing returns in prey capture rates. Using both
the results of an individual-based simulation and a field experiment dataset of gerbils foraging for seeds in an artificial
food patch located in the field, we demonstrate that our procedure can successfully detect and separate the effect of interference
from the combined overall effect of competition (i.e., interference plus exploitation).
Inon Scharf and Ido Filin contributed equally to this paper. 相似文献
73.
Ruben Pérez Lucía Calleros Ana Marandino Nicolás Sarute Gregorio Iraola Sofia Grecco Hervé Blanc Marco Vignuzzi Ofer Isakov Noam Shomron Lucía Carrau Martín Hernández Lourdes Francia Katia Sosa Gonzalo Tomás Yanina Panzera 《PloS one》2014,9(11)
Canine parvovirus (CPV), a fast-evolving single-stranded DNA virus, comprises three antigenic variants (2a, 2b, and 2c) with different frequencies and genetic variability among countries. The contribution of co-infection and recombination to the genetic variability of CPV is far from being fully elucidated. Here we took advantage of a natural CPV population, recently formed by the convergence of divergent CPV-2c and CPV-2a strains, to study co-infection and recombination. Complete sequences of the viral coding region of CPV-2a and CPV-2c strains from 40 samples were generated and analyzed using phylogenetic tools. Two samples showed co-infection and were further analyzed by deep sequencing. The sequence profile of one of the samples revealed the presence of CPV-2c and CPV-2a strains that differed at 29 nucleotides. The other sample included a minor CPV-2a strain (13.3% of the viral population) and a major recombinant strain (86.7%). The recombinant strain arose from inter-genotypic recombination between CPV-2c and CPV-2a strains within the VP1/VP2 gene boundary. Our findings highlight the importance of deep-sequencing analysis to provide a better understanding of CPV molecular diversity. 相似文献
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Endozoic microalgae were found in most snails collected from coral reefs and beachrock communities in the Red Sea. Algae were identified microscopically as well as by chromatography and spectrophotometry of pigment extracts. The algae were located in the hepatopancreas and the gonads, organs which are permanently concealed within the shell. According to pigment analysis, most of the endozoic algae belong the Chromophyta, perhaps dinoflagellates, except for a few chlorophytes. 相似文献
78.
Matthew Pettengill Simon Robson Megan Tresenriter José Luis Millán Anny Usheva Taiese Bingham Mirjam Belderbos Ilana Bergelson Sarah Burl Beate Kampmann Laura Gelinas Tobias Kollmann Louis Bont Ofer Levy 《The Journal of biological chemistry》2013,288(38):27315-27326
Extracellular adenosine, a key regulator of physiology and immune cell function that is found at elevated levels in neonatal blood, is generated by phosphohydrolysis of adenine nucleotides released from cells and catabolized by deamination to inosine. Generation of adenosine monophosphate (AMP) in blood is driven by cell-associated enzymes, whereas conversion of AMP to adenosine is largely mediated by soluble enzymes. The identities of the enzymes responsible for these activities in whole blood of neonates have been defined in this study and contrasted to adult blood. We demonstrate that soluble 5′-nucleotidase (5′-NT) and alkaline phosphatase (AP) mediate conversion of AMP to adenosine, whereas soluble adenosine deaminase (ADA) catabolizes adenosine to inosine. Newborn blood plasma demonstrates substantially higher adenosine-generating 5′-NT and AP activity and lower adenosine-metabolizing ADA activity than adult plasma. In addition to a role in soluble purine metabolism, abundant AP expressed on the surface of circulating neonatal neutrophils is the dominant AMPase on these cells. Plasma samples from infant observational cohorts reveal a relative plasma ADA deficiency at birth, followed by a gradual maturation of plasma ADA through infancy. The robust adenosine-generating capacity of neonates appears functionally relevant because supplementation with AMP inhibited whereas selective pharmacologic inhibition of 5′-NT enhanced Toll-like receptor-mediated TNF-α production in neonatal whole blood. Overall, we have characterized previously unrecognized age-dependent expression patterns of plasma purine-metabolizing enzymes that result in elevated plasma concentrations of anti-inflammatory adenosine in newborns. Targeted manipulation of purine-metabolizing enzymes may benefit this vulnerable population. 相似文献
79.
Amit?Savaya-Alkalay Ofer?Ovadia Assaf?Barki Amir?SagiEmail author 《Biological invasions》2018,20(1):137-149
All-male populations of the freshwater prawn Macrobrachium rosenbergii were recently produced by a novel temporal RNA interference (RNAi)-based biotechnology for aquaculture purposes. This biotechnology opens the way to the wide use of all-male prawn populations as sustainable biocontrol agents against invading populations of freshwater snails, for which there is currently no environmentally friendly solution. Among the most damaging of the invasive freshwater snail species are the apple snails (Pomacea spp.), which inflict major damage on natural ecosystems and rice fields. The proposed use of all-male prawn populations as environmentally friendly biocontrol agents against invasive freshwater snails has several advantages: efficient predation by the prawns over a wide range of freshwater snails, the ready availability of the prawns, and the monosex non-reproductive nature of the biocontrol agents. Since the aquatic predators are strongly size selective, we quantified the predation rate as a function of body size of both predator and prey (M. rosenbergii and P. caniculata). Medium-sized and large prawns (~10–30 g) efficiently preyed small and medium-sized snails (up to 15 mm), while small prawns (up to 4 g) immediately and completely eradicated snail hatchlings. Medium-sized prawns (~22 g) exterminated a significant fraction of snail biomass within 24 h (up to 58% of their body mass) after being introduced into a tank of snails. A typical ‘climbing-to-the surface’ anti-predator behavior of the snails was recorded. The potential of all-male prawns as efficient biocontrol agents over hatchling and adult apple snails as part of an integrated pest management program is discussed. Our experiments set the stage for evaluating the ecological and economic implications of this generic solution for a wide variety of habitats. 相似文献
80.
ICAMs Are Not Obligatory for Functional Immune Synapses between Naive CD4 T Cells and Lymph Node DCs