Investigation on Opisthorchis felineus occurrence and life cycle in Italy

Opisthorchiasis is a fish borne parasitic infection caused by helminths of the genus Opisthorchis (Digenea, Opisthorchiidae), affecting humans and other fish-eating mammals. Despite Opisthorchis felineus was first described in Italy in 1884, no cases of human opisthorchiasis were reported in this country until 2004; from then on, 4 outbreaks due to this species have been recorded in Central Italy. Following the more relevant of these outbreaks, involving 34 people in August 2007, snails, fishes and fecal samples collected from the Bolsena and Bracciano lakes (Central Italy) were analyzed in order to define the cycle of O. felineus in the area and investigate its prevalence in the different hosts. Pools of 20-40 snails each (4983 specimens altogether) of the genus Bithynia were analyzed by PCR for parasite DNA detection. Eight hundred and ninety-four fish belonging to 12 species were collected from the two lakes and tested for metacercariae both by muscle compression and digestion techniques. Eighty-seven fecal samples of 5 putative definitive host species were collected very close to the two lakes and tested for parasite eggs detection by formalin-ethyl acetate concentration technique. Identification at the species level of metacercariae and eggs, respectively, from fish and stool was confirmed by PCR analysis and sequencing. O. felineus DNA was detected in 0.08% (overall minimum infection rate) of snails of the genus Bithynia from the two lakes. The tench, Tinca tinca, was the only fish found infested in both lakes (prevalence 88.5%). O. felineus eggs were found only in cat feces (prevalence 46.4%). The tench represents the only threat for the human consumption in the study area while Coregonus sp., the most economically important species for the local fishery and frequently consumed raw marinated, resulted to be not infected. The high prevalence recorded both in fish and in definitive host suggests a widespread and massive presence of the parasite in the area. Further studies are needed to better investigate the possible role of some cyprinids species as intermediate hosts, in order to check their safety for human consumption.     

The anisotropic elasticity of the plant cell wall

Summary The plant cell wall is treated as a two phase fibre composite material in which the fibres are dispersed, in an isotropic matrix, in the plane of the cell wall with an angular distribution f(). If f () can be represented by a gaussian it is shown that the elastic stiffness constants of the cell wall can be easily evaluated. The theory is applied to a model of the earlywood of Pinus radiata and the theoretical variation of the longitudinal Young's Modulus with mean fibrilar direction is compared with that determined experimentally.

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Zusammenfassung Die pflanzliche Zellwand wird im allgemeinen behandelt wie ein im wesentlichen aus zwei Phasen bestehendes Fasermaterial, bei dem die Fasern in einer isotropen Matrixsubstanz gelöst und in der Zellwandebene mit einem Winkel f() verteilt sind. Sofern f() normal verteilt ist, können die elastischen Konstanten der Zellwand verhältnismäßig einfach berechnet werden. Diese Theorie wird auf das Modell von Kiefern-Frühholz (Pinus radiata) angewendet, und die theoretisch ermittelte Änderung des longitudinalen Youngs Moduls mit der mittleren Faserrichtung wird mit experimentell bestimmten Werten verglichen.

     

The longitudinal Young's modulus of Pinus radiata

Summary The variation of the longitudinal Young's modulus with mean cellulose microfibril angle of the wood substance of the earlywood of a softwood has been determined from small clear samples.The longitudinal Young's modulus falls steeply as the angle between the longitudinal axis and the mean microfibril direction in the cell walls increases. The variation has been explained in both form and magnitude by applying the elastic theory of a fibre composite material with distributed fibre directions to a model of the experimental material. It confirms the two phase concepts of the plant cell wall, as far as the elastic properties are concerned, of rigid crystalline microfibrils embedded in an isotropic matrix of amorphous and paracrystalline materials.

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Zusammenfassung Die Änderung des Young-Moduls in longitudinaler Richtung mit dem mittleren Winkel der Cellulose-Mikrofibrillen in der Frühholzsubstanz von Nadelholz wurde an kleinen, fehlerfreien Proben bestimmt.Der longitudinale Young-Modul fällt mit zunehmendem Winkel zwischen Längsachse und mittlerer Mikrofibrillen-Richtung in der Zellwand steil ab.Die Änderung wurde nach Form und Größe durch Anwendung der Elastizitätstheorie für ein faseriges Material mit wechselnden Faserrichtungen auf ein Modell aus dem Versuchsmaterial erklärt. Das Zwei-Phasen-Modell der Pflanzenzellwand wird damit bestätigt, soweit es sich um die elastischen Eigenschaften von starren, kristallinen Cellulose-Mikrofibrillen handelt, die in einer isotropen Matrix aus amorphem, parakristallinen Material eingebettet sind.

     

Theory of X-ray measurement of microfibril angle in wood

Summary The property of fibre symmetry as exhibited by wood cellulose can be used to derive an explicit relationship between the orientation of a cellulose microfibril and the orientation of the X-ray beam diffracted by any of its crystallographic planes. The solution applies to a microfibril of any orientation and so is well suited to evaluating the microfibril angle distribution in wood containing cells of any cross-sectional shape. The (002) and (040) reflections of cellulose have complementary properties that could be exploited to enable current problems associated with the use of each individually for evaluating the mean microfibril angle of the S2 layer to be overcome. It is expected that it will be possible to measure the microfibril angle distribution throughout the whole cell wall and also measure the average cell cross-section of a wood sample, by analysing (002) and (040) diffraction profiles in conjunction with each other.This work is supported by the NZ Foundation for Research, Science and Technology under contract # UOC 401     

An Integrated Population Model From Constant Effort Bird-Ringing Data

Data from annual bird-ringing programs, in which catch effort is standardized, are routinely used to index abundance, productivity, and adult survival. Efficient models have been developed for each. Such monitoring schemes, based on ringing across a number of sites, are perhaps unique in providing this combination of demographic information and make the data particularly amenable to an integrated approach to population modeling. We develop a Bayesian approach and a deterministic population model uniting abundance, productivity, and survival. The method is applied to sedge warbler Acrocephalus schoenobaenus data from the British Trust for Ornithology’s Constant Effort Sites scheme. The possibility of “transient” birds needs to be incorporated within this analysis. We demonstrate how current methodology can efficiently be extended to use additional data from multiple within year recaptures when controlling for transience. Supplemental materials for this article are available online.