Search results for "iNOS"

Within-host evolution decreases virulence in an opportunistic bacterial pathogen

2015

Abstract Background Pathogens evolve in a close antagonistic relationship with their hosts. The conventional theory proposes that evolution of virulence is highly dependent on the efficiency of direct host-to-host transmission. Many opportunistic pathogens, however, are not strictly dependent on the hosts due to their ability to reproduce in the free-living environment. Therefore it is likely that conflicting selection pressures for growth and survival outside versus within the host, rather than transmission potential, shape the evolution of virulence in opportunists. We tested the role of within-host selection in evolution of virulence by letting a pathogen Serratia marcescens db11 sequent…

Euparyphium albuferensis and Echinostoma friedi (Trematoda: Echinostomatidae): Experimental cercarial transmission success in sympatric snail communi…

2008

Euparyphium albuferensis and Echinostoma friedi cercarial infectivity to four species of sympatric snails was exam- ined under single- or multiple-choice laboratory conditions to show the level of parasite-snail host compatibility. Radix peregra, Lymnaea fuscus, Physella acuta and Gyraulus chinensis act as second intermediate hosts of both parasite species although differ- ent cercarial transmission success (CTS) was observed. In single-host experiments, R. peregra and P. acuta showed a high de- gree of compatibility with E. albuferensis, while only P. acuta in the case of E. friedi. In two-choice snail communities, a snail with high CTS increased the values of another with low compatibilit…

Helminth-Trematode: Echinostoma

2014

The term, echinostomes, includes those digeneans belonging to the family Echinostomatidae. Echinostomes are a rather heterogeneous group of cosmopolitan hermaphroditic digeneans that inhabit, as adults, the intestine of a great spectrum of vertebrate hosts, such as birds, mammals and, occasionally, reptiles and fishes. They can also parasitize humans causing the food-borne infection called echinostomiasis. The definitive hosts become infected after ingestion of the second intermediate host harboring the encysted metacercariae. Clinical symptoms of echinostomiasis include abdominal pain, violent watery diarrhea, and anorexia. The disease occurs focally and transmission is linked to fresh or …

Criteria for species determination in the 'revolutum' group of Echinostoma.

2004

Coincidental loss of bacterial virulence in multi-enemy microbial communities.

2014

The coincidental virulence evolution hypothesis suggests that outside-host selection, such as predation, parasitism and resource competition can indirectly affect the virulence of environmentally-growing bacterial pathogens. While there are some examples of coincidental environmental selection for virulence, it is also possible that the resource acquisition and enemy defence is selecting against it. To test these ideas we conducted an evolutionary experiment by exposing the opportunistic pathogen bacterium Serratia marcescens to the particle-feeding ciliate Tetrahymena thermophila, the surfacefeeding amoeba Acanthamoeba castellanii, and the lytic bacteriophage Semad11, in all possible combi…

Temperature-related changes in polar cyanobacterial mat diversity and toxin production

2012

This study documents the effects of warming on cyanobacterial mats from the Arctic and Antarctica. It describes toxin production in such mats and provides experimental evidence that increased temperatures could shift mat cyanobacterial species diversity from cold-loving species towards predominance of cold-tolerant and toxin-producing species.

First Record of the Genus Acanthixalus Laurent, 1944 from the Upper Guinean Rain Forest, West Africa, with the Description of a New Species

2003

Abstract We describe a new species of Acanthixalus from southwestern Ivory Coast. Acanthixalus sonjae sp. nov. differs from the Central African Acanthixalus spinosus genetically by 4.6 % in the investigated 16S rRNA. Morphologically adult frogs are very similar to A. spinosus. Male A. sonjae have wider heads and probably smaller gular glands than A. spinosus. Tadpoles of A. sonjae differ by much longer tails. Acanthixalus sonjae males are apparently mute. The new species is semiaquatic and lives in large water-filled cavities of trees in secondary and primary rain forest. Tadpoles complete metamorphosis in three months. They are at least partly carnivorous.

Beam test results of IHEP-NDL Low Gain Avalanche Detectors(LGAD)

2020

A High-Granularity Timing Detector (HGTD) is proposed based on the Low-Gain Avalanche Detector (LGAD) for the ATLAS experiment to satisfy the time resolution requirement for the up-coming High Luminosity at LHC (HL-LHC). We report on beam test results for two proto-types LGADs (BV60 and BV170) developed for the HGTD. Such modules were manufactured by the Institute of High Energy Physics (IHEP) of Chinese Academy of Sciences (CAS) collaborated with Novel Device Laboratory (NDL) of the Beijing Normal University. The beam tests were performed with 5 GeV electron beam at DESY. The timing performance of the LGADs was compared to a trigger counter consisting of a quartz bar coupled to a SiPM read…

Photosensitivity of SiO2–Al and SiO2–Na glasses under ArF (193 nm) laser

2009

Abstract Photosensitivity of SiO 2 –Al and SiO 2 –Na glass samples was probed by means of the induced optical absorption and luminescence as well as by electron spin-resonance (ESR) after irradiation with excimer-laser photons (ArF, 193 nm). Permanent visible darkening in the case of SiO 2 –Al and transient, life time about one hour, visible darkening in the case of SiO 2 –Na was found under irradiation at 290 K. No darkening was observed at 80 K for either kind of material. This investigation is dedicated to revealing the electronic processes responsible for photosensitivity at 290 and 80 K. The photosensitivity of both materials is related to impurity defects excited directly in the case …

EFFECT OF THE IMPase INHIBITOR L690,330 ON SEA URCHIN DEVELOPMENT

1998

Abstract A variety of concentrations of the IMPase inhibitor L690,330 were added to sea urchin embryos. Immediate arrest of development was obtained for concentrations from 7.5 m m on. Concentrations lower than 3.5 m m permitted gastrulation but inhibited skeletogenesis and disturbed elongation along the animal–vegetal axis. The latter results are similar to those obtained by counteracting lithium effect with myoinositol, which are suggested to be due to partial relief of IMPase inhibition.